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1

Perceptual interaction of the harmonic source and noise in voice  

PubMed Central

Although the amount of inharmonic energy (noise) present in a human voice is an important determinant of vocal quality, little is known about the perceptual interaction between harmonic and inharmonic aspects of the voice source. This paper reports three experiments investigating this issue. Results indicate that perception of the harmonic slope and of noise levels are both influenced by complex interactions between the spectral shape and relative levels of harmonic and noise energy in the voice source. Just-noticeable differences (JNDs) for the noise-to-harmonics ratio (NHR) varied significantly with the NHR and harmonic spectral slope, but NHR had no effect on JNDs for NHR when harmonic slopes were steepest, and harmonic slope had no effect when NHRs were highest. Perception of changes in the harmonic source slope depended on NHR and on the harmonic source slope: JNDs increased when spectra rolled off steeply, with this effect in turn depending on NHR. Finally, all effects were modulated by the shape of the noise spectrum. It thus appears that, beyond masking, understanding perception of individual parameters requires knowledge of the acoustic context in which they function, consistent with the view that voices are integral patterns that resist decomposition.

Kreiman, Jody; Gerratt, Bruce R.

2012-01-01

2

REVIEW ARTICLE: Harmonically mode-locked semiconductor-based lasers as high repetition rate ultralow noise pulse train and optical frequency comb sources  

NASA Astrophysics Data System (ADS)

Recent experimental work on semiconductor-based harmonically mode-locked lasers geared toward low noise applications is reviewed. Active, harmonic mode-locking of semiconductor-based lasers has proven to be an excellent way to generate 10 GHz repetition rate pulse trains with pulse-to-pulse timing jitter of only a few femtoseconds without requiring active feedback stabilization. This level of timing jitter is achieved in long fiberized ring cavities and relies upon such factors as low noise rf sources as mode-lockers, high optical power, intracavity dispersion management and intracavity phase modulation. When a high finesse etalon is placed within the optical cavity, semiconductor-based harmonically mode-locked lasers can be used as optical frequency comb sources with 10 GHz mode spacing. When active mode-locking is replaced with regenerative mode-locking, a completely self-contained comb source is created, referenced to the intracavity etalon.

Quinlan, F.; Ozharar, S.; Gee, S.; Delfyett, P. J.

2009-10-01

3

Ratchets driven by harmonic and white noise  

Microsoft Academic Search

The synthesis of overdamped Brownian motion in a periodic potential which lacks reflection symmetry (ratchet device) with unbiased nonequilibrium forces ?(t) yields an ordered, directed particle current. In this work, ?(t) is made up of a noisy oscillator dynamics (harmonic noise). Such noise is able to account for inertial dynamic features; as a consequence we observe multiple current reversals upon

R. Bartussek; P. Hänggi; B. Lindner; L. Schimansky-Geier

1997-01-01

4

An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs  

SciTech Connect

The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed.

Huang, Z.; /SLAC

2006-12-11

5

A LOW NOISE RF SOURCE FOR RHIC.  

SciTech Connect

The Relativistic Heavy Ion Collider (RHIC) requires a low noise rf source to ensure that beam lifetime during a store is not limited by the rf system. The beam is particularly sensitive to noise from power line harmonics. Additionally, the rf source must be flexible enough to handle the frequency jump required for rebucketing (transferring bunches from the acceleration to the storage rf systems). This paper will describe the design of a Direct Digital Synthesizer (DDS) based system that provides both the noise performance and the flexibility required.

HAYES,T.

2004-07-05

6

Directivity of railway noise sources  

NASA Astrophysics Data System (ADS)

In the Harmonoise project the description of vertical and horizontal directivities of railway noise sources has been required. Other features of the source description are sound power level spectra in one-third octave bands as a function of speed and the physical location of the different sound sources. Based on systematic investigations methods to measure and to determine the directivities of railway noise sources are presented in this paper. The determination of the directivity of rolling noise is discussed in detail. For the directivities of traction noise and aerodynamic noise the discussion is more analytical because of limited access to relevant data. For each type of main railway noise source, i.e. rolling noise, traction noise and aerodynamic noise, default directivity functions are proposed for the use in the source description of railway noise. These default directivity functions will be subject to revisions when more accurate data become available.

Zhang, Xuetao; Jonasson, Hans G.

2006-06-01

7

Diffusion in Hamiltonian systems driven by harmonic noise  

Microsoft Academic Search

We study the dynamics of randomly perturbed integrable Hamiltonian systems. In the limit of small perturbations, we show that the distribution function of the action variable satisfies a Fokker-Planck equation whose diffusion coefficient depends on the correlation function of the stochastic process. By using an harmonic noise we show the effect of resonances between the spectral density of the noise

Armando Bazzani; Luca Beccaceci

1998-01-01

8

Tonal strength of harmonic complex tones in machinery noise  

NASA Astrophysics Data System (ADS)

The sounds of machines often contain families of harmonically related sine waves that are referred to as harmonic complex tones. The perceived tonal strength of these types of sounds can adversely influence people's impressions of the sound. While a complex tone is comprised of many sine waves, usually only one prominent pitch sensation is produced. It can be argued that harmonic complex tones are perceived as a single entities, not as a sum of individual tones. A series of psychoacoustics tests was conducted to evaluate tonal prominence of harmonic complex tones. Two sounds of equal loudness were played to subjects. One was a harmonic complex tone in noise and the other was a single tone in noise. Subjects were asked to equalize the perceived tonalness of the two sounds by adjusting the tone to noise ratio of the single tone in noise. Tonalness and Terhardt's pitch perception models were applied to the pairs of sounds used in each test. The feasibility of replacing harmonic complex tones with a tonally equivalent simple sound was investigated, and strong correlations between Aures' tonality for the simple and complex tones were found.

Lee, Kyoung Hoon; Davies, Patricia; Surprenant, Aimee M.

2005-09-01

9

Speech synthesis with pitch modification using harmonic plus noise model  

NASA Astrophysics Data System (ADS)

In harmonic plus noise model (HNM) based speech synthesis, the input signal is modeled as two parts: the harmonic part using amplitudes and phases of the harmonics of the fundamental and the noise part using an all-pole filter excited by random white Gaussian noise. This method requires relatively less number of parameters and computations, provides good quality output, and permits pitch and time scaling without explicit estimation of vocal tract parameters. Pitch scaling to synthesize the speech with interpolated original amplitudes and phases at the multiples of the scaled pitch frequency results in an unnatural quality. Our investigation for obtaining natural quality output showed that the frequency scale of the amplitudes and phases of the harmonics of the original signal needed to be modified by a speaker dependent warping function. The function was obtained by studying the relationship between pitch frequency and formant frequencies for the three cardinal vowels naturally occurring with different pitches in a passage with intonation. Listening tests showed that good quality speech was obtained by linear frequency scaling of the amplitude and phase spectra, by the same factor as the pitch-scaling.

Lehana, Parveen K.; Pandey, Prem C.

2003-10-01

10

Rapporteur's report, session 2: Other sources, including maintenance noise, freightyards, locomotive noise, station noise, etc  

Microsoft Academic Search

The major sources of noise, excluding through train noise, were identified as locomotive noise, maintenance noise and freight marshalling noise. The biggest single problem appeared, from social survey data in the U.K., to be railway maintenance noise, which was difficult to control effectively. Locomotive noise was also a problem and it should be productive to diagnose the sources of noise

J. G. Walker

1979-01-01

11

Harmonic source and type identification in a radial distribution system  

Microsoft Academic Search

To aid in locating the source and type of harmonics in a distribution system, a computer program called HARM TRACER has been developed. HARM TRACER is a reverse harmonic power flow study program which traces the flow of harmonics in a radial distribution system from the point of measurement to the harmonic source or sources. It does so by considering

Asrat Teshome

1991-01-01

12

Low noise constant current source for bias dependent noise measurements  

Microsoft Academic Search

A low noise constant current source used for measuring the 1\\/f noise in disordered systems in ohmic as well as nonohmic regime is described. The source can supply low noise constant current starting from as low as 1 muA to a few tens of milliampere with a high voltage compliance limit of around 20 V. The constant current source has

D. Talukdar; R. K. Chakraborty; Suvendu Bose; K. K. Bardhan

2011-01-01

13

Low noise constant current source for bias dependent noise measurements.  

PubMed

A low noise constant current source used for measuring the 1?f noise in disordered systems in ohmic as well as nonohmic regime is described. The source can supply low noise constant current starting from as low as 1 ?A to a few tens of milliampere with a high voltage compliance limit of around 20 V. The constant current source has several stages, which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noise voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described. PMID:21280844

Talukdar, D; Chakraborty, R K; Bose, Suvendu; Bardhan, K K

2011-01-01

14

Low noise constant current source for bias dependent noise measurements  

SciTech Connect

A low noise constant current source used for measuring the 1/f noise in disordered systems in ohmic as well as nonohmic regime is described. The source can supply low noise constant current starting from as low as 1 {mu}A to a few tens of milliampere with a high voltage compliance limit of around 20 V. The constant current source has several stages, which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noise voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described.

Talukdar, D.; Bose, Suvendu; Bardhan, K. K. [Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Chakraborty, R. K. [Bidhannagar College, EB - 2, Bidhannagar, Kolkata 700064 (India)

2011-01-15

15

Low noise constant current source for bias dependent noise measurements  

NASA Astrophysics Data System (ADS)

A low noise constant current source used for measuring the 1/f noise in disordered systems in ohmic as well as nonohmic regime is described. The source can supply low noise constant current starting from as low as 1 ?A to a few tens of milliampere with a high voltage compliance limit of around 20 V. The constant current source has several stages, which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noise voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described.

Talukdar, D.; Chakraborty, R. K.; Bose, Suvendu; Bardhan, K. K.

2011-01-01

16

Low noise constant current source for bias dependent noise measurements  

Microsoft Academic Search

A low noise constant current source used for measuring the $1\\/f$ noise in\\u000adisordered systems in ohmic as well as non-ohmic regime is described. The\\u000asource can supply low noise constant current starting from as low as 1 $\\\\mu$A\\u000ato a few tens of mA with a high voltage compliance limit of around 20 Volts.\\u000aThe constant current source has

D. Talukdar; R. K. Chakraborty; Suvendu Bose; K. K. Bardhan

2010-01-01

17

SIW-Based W-Band Low Phase-Noise Injection-Locked Harmonic Oscillator  

NASA Astrophysics Data System (ADS)

A W-band planar injection-locked harmonic oscillator (ILHO) based on substrate integrated waveguide (SIW) is implemented. This ILHO has a free-running output frequency around 94.6 GHz while the technique of harmonic extraction from diodes is used as a frequency multiplier. It has an output locking bandwidth of 300 MHz (from 94.45 to 94.75 GHz) as injecting a signal around 47.3 GHz with the fundamental injection-locked behavior, and the output power is more than 5.8 dBm. The combination of simple synchronization with a low-frequency reference signal allows the generation of stable and low phase-noise W-band signals with a fully integrated planar source.

Liu, Yong; Tang, Xiao-Hong; Wu, Tao

2012-05-01

18

SIW-Based W-Band Low Phase-Noise Injection-Locked Harmonic Oscillator  

NASA Astrophysics Data System (ADS)

A W-band planar injection-locked harmonic oscillator (ILHO) based on substrate integrated waveguide (SIW) is implemented. This ILHO has a free-running output frequency around 94.6 GHz while the technique of harmonic extraction from diodes is used as a frequency multiplier. It has an output locking bandwidth of 300 MHz (from 94.45 to 94.75 GHz) as injecting a signal around 47.3 GHz with the fundamental injection-locked behavior, and the output power is more than 5.8 dBm. The combination of simple synchronization with a low-frequency reference signal allows the generation of stable and low phase-noise W-band signals with a fully integrated planar source.

Liu, Yong; Tang, Xiao-Hong; Wu, Tao

2012-09-01

19

Annoyance due to Combined Community Noise Sources  

NASA Astrophysics Data System (ADS)

The relative contributions of various major noise sources to annoyance have not been clearly established. Two experiments were conducted to assess the effect of combined community noise sources on annoyance. The first experiment established baseline relationships between annoyance and noise level for three community noise sources presented individually (jet aircraft flyovers, traffic, and air conditioner) which differed from one another in spectral and temporal characteristics. Forty-eight subjects rated the annoyance at the end of each session for each noise source presented separately at four different noise levels. The results indicated that the slope of the linear relationship between annoyance and noise level for traffic noise was significantly different from that of aircraft and of air conditioner noise, which had the same slopes. In the second experiment, aircraft noise was defined as the major noise source and traffic and air conditioner as background noise sources. The effects of the noise level differences between aircraft and background noise for three total noise levels and type of background noise source on rated annoyance were determined. This experiment required 216 subjects to make either total or source-specific annoyance judgments, or a combination of the two, for each of 14 experimental noise conditions presented as sessions. For both experiments, an additional dependent measure was investigated as a possible objective correlate to rated annoyance. This measure was the amount of the subjects' subconscious body movements as measured by accelerometers mounted underneath their chairs. Both the type of background noise source and the type or combination of annoyance ratings requested were found to have an effect on annoyance. The results of this research have important implications for community noise criteria and for the application of community noise response prediction models. Both should be designed to account for spectral, duration, and temporal differences between noise sources as well as noise levels. Furthermore, the type of annoyance of interest, e.g., total or source-specific, should be considered. As an attempt to find a correlated measure of annoyance, the body movement results were inconclusive for both experiments.

Willshire, Kelli Francisco

20

Imaging of directional distributed noise sources  

Microsoft Academic Search

This study relates to the acoustic imaging of noise sources that are distributed and strongly directional, such as in turbulent jets. The goal is to generate high-resolution noise source maps with self-consistency, i.e., their integration over the extent of the noise source region gives the far-field pressure auto-spectrum for a particular emission direction. Self-consistency is possible by including a directivity

Dimitri Papamoschou

2011-01-01

21

Excess noise in fiber gyroscope sources  

Microsoft Academic Search

Excess noise was measured in three potential interferometric fiber gyroscope sources, superluminescent diodes at 0.83 and 1.3 ?m, and a superfluorescent fiber source at 1.06 ?m. All three sources showed limiting signal-to-noise ratios in the 128-132 dB range (1 Hz bandwidth at 100 kHz), in agreement with their measured linewidths. The impact of the excess noise on the fiber gyro

W. K. Burns; R. P. Moeller; A. Dandridge

1990-01-01

22

Reduction of Blade-Vortex Interaction Noise Using Higher Harmonic Pitch Control.  

National Technical Information Service (NTIS)

An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rot...

T. F. Brooks E. R. Booth J. R. Jolly W. T. Yeager M. L. Wilbur

1989-01-01

23

2-D HARMONIC RETRIEVAL IN MULTIPLICATIVE AND ADDITIVE NOISE BASED ON CHIRP Z-TRANSFORM  

Microsoft Academic Search

The two-dimensional (2-D) harmonic retrieval method in multiplicative and additive noise based on 2-D chirp z-transform (CZT) is discussed in this paper. Unlike 2-D FFT, the 2-D CZT can improve the spectral resolution without increasing the size of the observation data and fine the spectra of 2-D harmonics in multiplicative and additive noise. Hence, the resolution and accuracy of the

Shiyong Yang; Hongwei Li; Cheng Wu; Zhiming Li

2006-01-01

24

Estimating the frequency interval of a regularly spaced multicomponent harmonic line signal in colored noise  

NASA Astrophysics Data System (ADS)

The radar returns from some classes of time-varying point targets can be represented by the discrete-time signal plus noise model: xt equals st plus [vt plus (eta) t] equals (summation)i equals o P minus 1 Aiej2(pi f(i)/f(s)t) plus vt plus (eta) t, t (epsilon) 0, . . ., N minus 1, fi equals kfI plus fo where the received signal xt corresponds to the radar return from the target of interest from one azimuth-range cell. The signal has an unknown number of components, P, unknown complex amplitudes Ai and frequencies fi. The frequency parameters fo and fI are unknown, although constrained such that fo less than fI/2 and parameter k (epsilon) {minus u, . . ., minus 2, minus 1, 0, 1, 2, . . ., v} is constrained such that the component frequencies fi are bound by (minus fs/2, fs/2). The noise term vt, is typically colored, and represents clutter, interference and various noise sources. It is unknown, except that (summation)tvt2 less than infinity; in general, vt is not well modelled as an auto-regressive process of known order. The additional noise term (eta) t represents time-invariant point targets in the same azimuth-range cell. An important characteristic of the target is the unknown parameter, fI, representing the frequency interval between harmonic lines. It is desired to determine an estimate of fI from N samples of xt. We propose an algorithm to estimate fI based on Thomson's harmonic line F-Test, which is part of the multi-window spectrum estimation method and demonstrate the proposed estimator applied to target echo time series collected using an experimental HF skywave radar.

Frazer, Gordon J.; Anderson, Stewart J.

1997-10-01

25

Lifetime increase using passive harmonic cavities insynchrotronlight sources  

SciTech Connect

Harmonic cavities have been used in storage rings to increase beam lifetime and Landau damping by lengthening the bunch.The need for lifetime increase is particularly great in the present generation of low to medium energy synchrotron light sources where the small transverse beam sizes lead to relatively short lifetimes from large-angle intrabeam (Touschek) scattering. We review the beam dynamics of harmonic radiofrequency (RF) systems and discuss optimization of the beam lifetime using passive harmonic cavities.

Byrd, J.M.; Georgsson, M.

2000-09-22

26

Lifetime increase using passive harmonic cavities in synchrotron light sources  

NASA Astrophysics Data System (ADS)

Harmonic cavities have been used in storage rings to increase beam lifetime and Landau damping by lengthening the bunch. The need for lifetime increase is particularly great in the present generation of low to medium energy synchrotron light sources where the small transverse beam sizes lead to relatively short lifetimes from large-angle intrabeam (Touschek) scattering. We review the beam dynamics of harmonic radio-frequency systems and discuss optimization of the beam lifetime using passive harmonic cavities.

Byrd, J. M.; Georgsson, M.

2001-03-01

27

Pitch strength of noise-vocoded harmonic tone complexes in normal-hearing listeners  

PubMed Central

To study the role of harmonic structure in pitch perception, normal-hearing listeners were tested using noise-vocoded harmonic tone complexes. When tested in a magnitude judgment procedure using vocoded versions generated with 2–128 channels, judgments of pitch strength increased systematically as the number of channels increased and reflected acoustic cues based on harmonic peak-to-valley ratio, but not cues based on periodicity strength. When tested in a fundamental frequency discrimination task, listeners correctly recognized the direction of pitch change with as few as eight noise-vocoded channels. The results suggest that spectral processing contributes substantially to pitch perception in normal-hearing listeners.

Shofner, William P.; Campbell, Jeannine

2012-01-01

28

Investigation of hydraulic transmission noise sources  

NASA Astrophysics Data System (ADS)

Advanced hydrostatic transmissions and hydraulic hybrids show potential in new market segments such as commercial vehicles and passenger cars. Such new applications regard low noise generation as a high priority, thus, demanding new quiet hydrostatic transmission designs. In this thesis, the aim is to investigate noise sources of hydrostatic transmissions to discover strategies for designing compact and quiet solutions. A model has been developed to capture the interaction of a pump and motor working in a hydrostatic transmission and to predict overall noise sources. This model allows a designer to compare noise sources for various configurations and to design compact and inherently quiet solutions. The model describes dynamics of the system by coupling lumped parameter pump and motor models with a one-dimensional unsteady compressible transmission line model. The model has been verified with dynamic pressure measurements in the line over a wide operating range for several system structures. Simulation studies were performed illustrating sensitivities of several design variables and the potential of the model to design transmissions with minimal noise sources. A semi-anechoic chamber has been designed and constructed suitable for sound intensity measurements that can be used to derive sound power. Measurements proved the potential to reduce audible noise by predicting and reducing both noise sources. Sound power measurements were conducted on a series hybrid transmission test bench to validate the model and compare predicted noise sources with sound power.

Klop, Richard J.

29

Ship sources of ambient noise  

Microsoft Academic Search

The rapid increase in world shipping results in an increase in low-frequency ambient noise at an average rate of about 1\\/2 dB per year. During the past 10 years there has been a virtual revolution in the sizes and speeds of merchant ships, resulting in significant increases in the noise radiated by the average ship. This trend is continuing. In

D. Ross

2005-01-01

30

Anomalous diffusive behavior of a harmonic oscillator driven by a Mittag-Leffler noise.  

PubMed

The diffusive behavior of a harmonic oscillator driven by a Mittag-Leffler noise is studied. Using the Laplace analysis we derive exact expressions for the relaxation functions of the particle in terms of generalized Mittag-Leffler functions and its derivatives from a generalized Langevin equation. Our results show that the oscillator displays an anomalous diffusive behavior. In the strictly asymptotic limit, the dynamics of the harmonic oscillator corresponds to an oscillator driven by a noise with a pure power-law autocorrelation function. However, at short and intermediate times the dynamics has qualitative difference due to the presence of the characteristic time of the noise. PMID:19658647

Viñales, A D; Wang, K G; Despósito, M A

2009-07-01

31

A novel method based on neural networks to distinguish between load harmonics and source harmonics in a power system  

Microsoft Academic Search

Utilities in recent years are experiencing increasing harmonic distortion problems. The harmonic voltages and currents deteriorate the power quality. This has lot of detrimental effect on equipments. A bigger issue is accurate determination of the source of harmonic distortion. Disputes arise between utility and customers regarding who is responsible for the harmonic distortions due to the lack of a reliable

Joy Mazumdar; Ronald G. Harley; Frank Lambert; Ganesh K. Venayagamoorthy

2005-01-01

32

Imaging of directional distributed noise sources  

NASA Astrophysics Data System (ADS)

This study relates to the acoustic imaging of noise sources that are distributed and strongly directional, such as in turbulent jets. The goal is to generate high-resolution noise source maps with self-consistency, i.e., their integration over the extent of the noise source region gives the far-field pressure auto-spectrum for a particular emission direction. Self-consistency is possible by including a directivity factor in the formulation of the source cross-spectral density. The resulting source distribution is based on the complex coherence, rather than the cross-spectrum, of the measured acoustic field. For jet noise, whose spectral nature changes with emission angle, it is necessary to conduct the measurements with a narrow-aperture array. Three coherence-based imaging methods were applied to a Mach 0.9 turbulent jet: delay-and-sum beamforming; deconvolution of the beamformer output; and direct spectral estimation that relies on minimizing the difference between the measured and modeled coherences of the acoustic field. The delay-and-sum beamforming generates noise source maps with strong spatial distortions and sidelobes. Deconvolution leads to a five-fold improvement in spatial resolution and significantly reduces the intensity of the sidelobes. The direct spectral estimation produces maps very similar to those obtained by deconvolution. The coherence-based noise source maps, obtained by deconvolution or direct spectral estimation, are similar at small and large observation angles relative to the jet axis.

Papamoschou, D.

2011-05-01

33

Separation of Individual Noise Sources from Compound Noise Measurements in Digital Circuits  

Microsoft Academic Search

Analysis of individual noise sources in pre-nanometer circuits cannot take into account the evolving reality of multiple noise sources interacting with each other. Noise measurement made at an evaluation node will reflect the cumulative effect of all the active noise sources, while individual and relative severity of various noise sources will determine what types of remedial steps can be taken,

V. P. Nigam; Masud H. Chowdhury; Roland Priemer

2006-01-01

34

Compound noise separation in digital circuits using blind source separation  

Microsoft Academic Search

Analysis of individual noise sources in pre-nanometer circuits cannot take into account the evolving reality of multiple noise sources interacting with each other. Noise measurement made at an evaluation node will reflect the cumulative effect of all the active noise sources, while individual and relative severity of various noise sources will determine what types of remedial steps can be taken,

Jingye Xu; Vivek P. Nigam; Abinash Roy; Masud H. Chowdhury

2008-01-01

35

Ocean wave sources of seismic noise  

NASA Astrophysics Data System (ADS)

Noise with periods 3 to 10 s, ubiquitous in seismic records, is expected to be mostly generated by pairs of ocean wave trains of opposing propagation directions with half the seismic frequency. Here we present the first comprehensive numerical model of microseismic generation by random ocean waves, including ocean wave reflections. Synthetic and observed seismic spectra are well correlated (r > 0.85). On the basis of the model results, noise generation events can be clustered in three broad classes: wind waves with a broad directional spectrum (class I), sea states with a significant contribution of coastal reflections (class II), and the interaction of two independent wave systems (class III). At seismic stations close to western coasts, noise generated by class II sources generally dominates, but it is intermittently outshined by the intense class III sources, limiting the reliability of seismic data as a proxy for storm climates. The modeled seismic noise critically depends on the damping of seismic waves. At some mid-ocean island stations, low seismic damping is necessary to reproduce the observed high level and smoothness of noise time series that result from a spatial integration of sources over thousands of kilometers. In contrast, some coastal stations are only sensitive to noise within a few hundreds of kilometers. This revelation of noise source patterns worldwide provides a wealth of information for seismic studies, wave climate applications, and new constraints on the possible directional distribution of wave energy.

Ardhuin, Fabrice; Stutzmann, Eleonore; Schimmel, Martin; Mangeney, Anne

2011-09-01

36

Brilliant high harmonic sources with extended cut-off  

SciTech Connect

The most challenging application of time resolved spectroscopy is to directly watch the structural and electronic dynamics. Here we present several ways for realizing laser driven x-ray sources, offering atomic spatial and temporal resolution. Our approaches are based on high harmonic generation and include quasi-phase matching in two successive gas jets, extending the cut-off by high harmonic generation in an ion channel, and amplification of HHG in a plasma based amplifier.

Seres, Josef; Spielmann, Christian [Institut fuer Optik und Quantenelektronik Friedrich Schiller Universitaet Jena, Max Wien Platz 07743 Jena (Germany); Physikalisches Institut EP1, Universitaet Wuerzburg, Am Hubland, 97074 Wuerzburg (Germany); Seres, Enikoe [Institut fuer Optik und Quantenelektronik Friedrich Schiller Universitaet Jena, Max Wien Platz 07743 Jena (Germany)

2010-02-02

37

Investigation of non-linear devices modeled as a harmonic current source  

Microsoft Academic Search

IEEE std. 519-1992 recommends that nonlinear devices can be modeled generally as a harmonic current source. However, some literatures propose that the voltage-source nonlinear devices actually behave as a harmonic voltage source. The need to verify if nonlinear devices can be treated as harmonic current sources in power system analysis and harmonic mitigation remains strong and challenging. In this paper,

Xiaodong Liang; William Jackson

2008-01-01

38

Reduction of blade-vortex interaction noise using higher harmonic pitch control  

Microsoft Academic Search

An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in Langley's Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of

Thomas F. Brooks; Earl R. Booth Jr.; J. Ralph Jolly Jr.; William T. Yeager Jr.; Matthew L. Wilbur

1989-01-01

39

Reduction of blade-vortex interaction noise through higher harmonic pitch control  

Microsoft Academic Search

An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in Langley's Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of

Thomas F. Brooks; Earl R. Booth Jr.; J. Ralph Jolly Jr.; William T. Yeager Jr.; Matthew L. Wilbur

1990-01-01

40

Fan Noise Source Diagnostic Test Computation of Rotor Wake Turbulence Noise  

Microsoft Academic Search

An important source mechanism of fan broadband noise is the interaction of rotor wake turbulence with the fan outlet guide vanes. A broadband noise model that utilizes computed rotor flow turbulence from a RANS code is used to predict fan broadband noise spectra. The noise model is employed to examine the broadband noise characteristics of the 22-inch Source Diagnostic Test

M. Nallasamy; E. Envia; S. A. Thorp; A. Shabbir

2002-01-01

41

On the implementation of the harmonic plus noise model for concatenative speech synthesis  

Microsoft Academic Search

In concatenative speech synthesis systems, speech models are usually used to represent the speech signal. Recently, the harmonic plus noise model (HNM) has been proposed for concatenative speech synthesis with promising results. One main drawback of HNM is its complexity. In this paper, we review four different methods of reducing the complexity of HNM. These include, straight-forward synthesis(SF), synthesis using

Yannis Stylianou

2000-01-01

42

Consideration of some noise sources due to railway operation  

NASA Astrophysics Data System (ADS)

A number of railway operation noise sources other than those leading to the far field (largely wheel/rail), train pass-by noise, are identified and briefly discussed. People primarily affected by these may include railway staff and passengers on the train, railway trackside staff, and wayside residents. Both environmental pollution and hearing protection may be involved. Sources considered include the following: close proximity wheel/rail noise; locomotive noise; freight vehicle noise; warning signal noise; near field bridge noise; marshalling yard noise; flange squeal on tight curves; maintenance machine noise; and track machinery warning horn noise.

Stanworth, C. G.

1983-03-01

43

The importance of quadrupole sources in prediction of transonic tip speed propeller noise  

Microsoft Academic Search

A theoretical analysis is presented for the harmonic noise of high speed, open rotors. Far field acoustic radiation equations based on the Ffowcs-Williams\\/Hawkings theory are derived for a static rotor with thin blades and zero lift. Near the plane of rotation, the dominant sources are the volume displacement and the rho U(2) quadrupole, where u is the disturbance velocity component

D. B. Hanson; M. R. Fink

1978-01-01

44

The importance of quadrupole sources in prediction of transonic tip speed propeller noise  

Microsoft Academic Search

A theoretical analysis is presented for the harmonic noise of high speed, open rotors. Far field acoustic radiation equations based on the Ffowcs Williams\\/Hawkings theory are derived for a static rotor with thin blades and zero lift. Near the plane of rotation, the dominant sources are the volume displacement and the varrhou2 quadrupole, where u is the disturbance velocity component

D. B. Hanson; M. R. Fink

1979-01-01

45

The first harmonic as a known source for wavefront correction  

NASA Astrophysics Data System (ADS)

It is demonstrated that distortion of a non-linearly generated first harmonic transmit beam due to a near-field aberrator is reduced as transmit pressure is increased. The first harmonic transmit beam is then used as a source for correction of aberration. In the first experiment, pieces of Lucite 11 mm and 24 mm thick were used as near-field aberrators. Beam plots of the fundamental and first harmonic were measured in a water tank with and without the aberrators present at multiple transmit voltages. The Lucite aberrator was then removed and an electronic aberrator with RMS delay error of 138 ns was applied to the transmit and receive apertures. The first harmonic reflected from the tip of a hydrophone was measured, and correcting delays were determined using a multi-lag least-means-squares cross-correlation method. Corrections were applied to an imaging beam transmitted at twice the frequency of the fundamental beam, the same frequency as the generated first-harmonic. Results from the Lucite experiments showed a -6 dB beam width improvement of 1.8 degrees when transmit voltage was increased from 20 volts to 80 volts. Results from first harmonic based correction of the electronic aberrator resulted in significant improvement in beam width and showed an average improvement of 16.8 dB in transmit beam signal level and 31.9 dB improvement in transmit-receive beam signal level.

Dianis, Scott W.; von Ramm, Olaf T.

2009-02-01

46

ANNOYANCE DUE TO COMBINED NOISE SOURCES  

Microsoft Academic Search

The development of double infrastructures, a motorway and a high speed railway line for example, leads to an increasing number of residents exposed simultaneously to several noise sources, each one having its own characteristics and eects. However, nowadays, this kind of situation can't be precisely qualified in terms of annoyance. The objective of the present study is on the one

S. Joncour; D. Cailhau; P.-E. Gautier; P. Champelovier; J. Lambert

2000-01-01

47

Aeroacoustic sources of motorcycle helmet noise.  

PubMed

The prevalence of noise in the riding of motorcycles has been a source of concern to both riders and researchers in recent times. Detailed flow field information will allow insight into the flow mechanisms responsible for the production of sound within motorcycle helmets. Flow field surveys of this nature are not found in the available literature which has tended to focus on sound pressure levels at ear as these are of interest for noise exposure legislation. A detailed flow survey of a commercial motorcycle helmet has been carried out in combination with surface pressure measurements and at ear acoustics. Three potential noise source regions are investigated, namely, the helmet wake, the surface boundary layer and the cavity under the helmet at the chin bar. Extensive information is provided on the structure of the helmet wake including its frequency content. While the wake and boundary layer flows showed negligible contributions to at-ear sound the cavity region around the chin bar was identified as a key noise source. The contribution of the cavity region was investigated as a function of flow speed and helmet angle both of which are shown to be key factors governing the sound produced by this region. PMID:21895059

Kennedy, J; Adetifa, O; Carley, M; Holt, N; Walker, I

2011-09-01

48

Reduction of blade-vortex interaction noise through higher harmonic pitch control  

NASA Astrophysics Data System (ADS)

An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in Langley's Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of matched flight conditions, where prescribed (open-loop) higher harmonic pitch was superimposed on the normal (baseline) collective and cyclic trim pitch. For the inflow-microphone noise measurements, advantage was taken of the reverberance in the hard walled tunnel by using a sound power determination approach. Initial findings from on-line data processing for three of the test microphones are reported for a 4/rev (4P) collective pitch control for a range of input amplitudes and phases. By comparing these results to corresponding baseline (no control) conditions, significant noise reductions (4 to 5 dB) were found for low-speed descent conditions, where helicopter BVI noise is most intense. For other rotor flight conditions, the overall noise was found to increase. All cases show increased vibration levels.

Brooks, Thomas F.; Booth, Earl R., Jr.; Jolly, J. Ralph, Jr.; Yeager, William T., Jr.; Wilbur, Matthew L.

1990-01-01

49

Reduction of blade-vortex interaction noise using higher harmonic pitch control  

NASA Astrophysics Data System (ADS)

An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in Langley's Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of matched flight conditions, where prescribed (open-loop) higher harmonic pitch was superimposed on the normal (baseline) collective and cyclic trim pitch. For the inflow-microphone noise measurements, advantage was taken of the reverberance in the hard walled tunnel by using a sound power determination approach. Initial findings from on-line data processing for three of the test microphones are reported for a 4/rev (4P) collective pitch control for a range of input amplitudes and phases. By comparing these results to corresponding baseline (no control) conditions, significant noise reductions (4 to 5 dB) were found for low-speed descent conditions, where helicopter BVI noise is most intense. For other rotor flight conditions, the overall noise was found to increase. All cases show increased vibration levels.

Brooks, Thomas F.; Booth, Earl R., Jr.; Jolly, J. Ralph, Jr.; Yeager, William T., Jr.; Wilbur, Matthew L.

1989-07-01

50

Inhomogeneity of the phase space of the damped harmonic oscillator under Lévy noise  

NASA Astrophysics Data System (ADS)

The damped harmonic oscillator under symmetric Lévy white noise shows inhomogeneous phase space, which is in contrast to the homogeneous phase space of the same oscillator under the Gaussian white noise, as shown in a recent paper [Sokolov, Ebeling, and Dybiec, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.041118 83, 041118 (2011)]. The inhomogeneity of the phase space shows correlation between the coordinate and the velocity of the damped oscillator under symmetric Lévy white noise. In the present work we further explore the physical origin of these distinguished features and find that it is due to the combination of the damped effect and heavy tail of the noise. We directly demonstrate this in the reduced coordinate x˜ versus velocity ? plots and identify the physics of the antiassociation of the coordinate and velocity.

Cao, Zhan; Wang, Yu-Feng; Luo, Hong-Gang

2012-04-01

51

Blind source separation of noisy harmonic signals for rotating machine diagnosis  

NASA Astrophysics Data System (ADS)

Blind source separation (BSS) consists of recovering signals from different physical sources from several observed combinations independently of the propagation medium. BSS is also a promising tool for non-destructive machine condition monitoring by vibration analysis, as it is intended to retrieve the signature of a single rotating machine from combinations of several working machines. In this way, BSS can be seen as a pre-processing step that improves the diagnosis. BSS methods generally assume observations that are either noise-free or corrupted with spatially distinct white noises. In the latter case, principal component analysis (PCA) is applied as a first step to filter out the noise and whiten the observations. Obviously, the efficiency of the whole separation procedure depends on the accuracy of the first step (PCA). However, in the real world, signals of rotating machine vibration may be severely corrupted with spatially correlated noises and therefore the signal subspace will not be correctly estimated with PCA. The purpose of this paper is to propose a `robust-to-noise' technique for the separation of rotating machine signals. The sources are assumed here to be periodic and so can be modelled as the sum of sinusoids of harmonic frequencies. A new estimator of the signal subspace and the whitening matrix is introduced which exploits the model of sinusoidal sources and uses spectral matrices of delayed observations to eliminate the influence of the noise. After whitening, the second step of source separation remains unchanged. Finally, performance of the algorithm is investigated with artificial data and experimental rotating machine vibration data.

Servière, C.; Fabry, P.

2004-04-01

52

TD-PSOLA versus harmonic plus noise model in diphone based speech synthesis  

Microsoft Academic Search

In an effort to select a speech representation for our next generation concatenative text-to-speech synthesizer, the use of two candidates is investigated; TD-PSOLA and the harmonic plus noise model, HNM. A formal listening test has been conducted and the two candidates have been rated regarding intelligibility, naturalness and pleasantness. Ability for database compression and computational load is also discussed. The

Ann Syrdal; Yannis Stylianou; Laurie Garrison; Alistair Conkie; Juergen Schroeter

1998-01-01

53

Asymptotic behavior of a harmonic oscillator driven by a generalized Mittag-Leffler noise  

NASA Astrophysics Data System (ADS)

The asymptotic behavior of a harmonic oscillator driven by a generalized Mittag-Leffler noise was studied by analyzing the generalized Langevin equation. The mean square displacement (MSD) and the velocity autocorrelation function (VACF) of a diffusing particle were obtained by using the Laplace transform method and Tauberian theorem. It was found that the MSD and VACF for various values of the parameters show a power-law decay, i.e. an anomalous diffusive behavior of the oscillator.

Sandev, Trifce; Tomovski, Živorad

2010-12-01

54

Rotor blade-vortex interaction noise reduction and vibration using higher harmonic control  

Microsoft Academic Search

The use of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) noise is examined by means of a rotor acoustic test. A dynamically scaled, four-bladed, articulated rotor model was tested in a heavy gas (Freon-12) medium. Acoustic and vibration measurements were made for a large range of matched flight conditions where prescribed (open loop) HHC pitch

Thomas F. Brooks; Earl R. Booth Jr.

1990-01-01

55

Identifying noise sources of time-delayed feedback systems  

NASA Astrophysics Data System (ADS)

We propose a novel method to identify noise sources of stochastic systems with time delays. In particular, we demonstrate how to distinguish between additive and multiplicative noise sources and to determine the structure of multiplicative and parametric noise sources of time-delayed human motor control systems.

Frank, T. D.; Beek, P. J.; Friedrich, R.

2004-07-01

56

Application of noise source identification techniques to information technology equipment  

Microsoft Academic Search

Conventional noise source identification techniques are usually associated with larger mechanical sources such as engines, gearboxes, and the like, having medium to high noise emissions. The IT industry presents a different problem-set, though, in that the noise sources are usually smaller and are relatively low level. However, this does not prevent use of these techniques, in that they can be

Roger Upton; Gijs Dirks

2005-01-01

57

Research on exterior noise source dentification of high speed trains  

Microsoft Academic Search

In order to clear about the major source, distribution and frequency characteristics of high speed trains exterior noise in operation, using the advanced noise identification and measure system of multi-channel microphone spoke array, the field tests of high-speed train noise were carried out. The results show that the major noise sources of high speed trains are wheel\\/rail rolling noise and

Jie Zhang; Yong Pan

2011-01-01

58

First-passage time of an inverted pendulum subject to high frequency harmonic and Gaussian white noise excitations  

Microsoft Academic Search

The first-passage time of an inverted pendulum subject to a combination of high frequency harmonic excitation and Gaussian white noise excitation is investigated. The high frequency harmonic excitation term is simplified to an equivalent autonomous nonlinear stiffness term by using the method of direct partition of motions. Then, the equations of motion of the equivalent system are reduced to an

Z. L. Huang; Z. Q. Zhu; X. L. Jin

2009-01-01

59

Clarification and measurements of high frequency harmonic resonance by a voltage sourced converter  

Microsoft Academic Search

This work presents the clarification and measurements of a high-order harmonic resonance phenomenon for voltage sourced converters. When a voltage sourced converter is connected to a power system through a cable, there is a possibility that small, high frequency, harmonic voltages due to the converter are magnified by series and parallel resonances. The cause of the high-order harmonic resonance is

Koji Temma; Fujio Ishiguro; Naohiro Toki; Isao Iyoda; John J. Paserba

2005-01-01

60

Assessing noise sources at synchrotron infrared ports  

PubMed Central

Today, the vast majority of electron storage rings delivering synchrotron radiation for general user operation offer a dedicated infrared port. There is growing interest expressed by various scientific communities to exploit the mid-IR emission in microspectroscopy, as well as the far infrared (also called THz) range for spectroscopy. Compared with a thermal (laboratory-based source), IR synchrotron radiation sources offer enhanced brilliance of about two to three orders of magnitude in the mid-IR energy range, and enhanced flux and brilliance in the far-IR energy range. Synchrotron radiation also has a unique combination of a broad wavelength band together with a well defined time structure. Thermal sources (globar, mercury filament) have excellent stability. Because the sampling rate of a typical IR Fourier-transform spectroscopy experiment is in the kHz range (depending on the bandwidth of the detector), instabilities of various origins present in synchrotron radiation sources play a crucial role. Noise recordings at two different IR ports located at the Swiss Light Source and SOLEIL (France), under conditions relevant to real experiments, are discussed. The lowest electron beam fluctuations detectable in IR spectra have been quantified and are shown to be much smaller than what is routinely recorded by beam-position monitors.

Lerch, Ph.; Dumas, P.; Schilcher, T.; Nadji, A.; Luedeke, A.; Hubert, N.; Cassinari, L.; Boege, M.; Denard, J.-C.; Stingelin, L.; Nadolski, L.; Garvey, T.; Albert, S.; Gough, Ch.; Quack, M.; Wambach, J.; Dehler, M.; Filhol, J.-M.

2012-01-01

61

Feedback and harmonic locking of slot-type optomechanical oscillators to external low-noise reference clocks  

NASA Astrophysics Data System (ADS)

We demonstrate feedback and harmonic locking of chip-scale slot-type optomechanical oscillators to external low-noise reference clocks, with suppressed timing jitter by three orders of magnitude. The feedback and compensation techniques significantly reduce the close-to-carrier phase noise, especially within the locking bandwidth for the integral root-mean-square timing jitter. Harmonic locking via high-order carrier signals is also demonstrated with similar phase noise and integrated root-mean-square timing jitter reduction. The chip-scale optomechanical oscillators are tunable over an 80-kHz range by tracking the reference clock, with potential applications in tunable radio-frequency photonics platforms.

Zheng, Jiangjun; Li, Ying; Goldberg, Noam; McDonald, Mickey; Luan, Xingsheng; Hati, Archita; Lu, Ming; Strauf, Stefan; Zelevinsky, Tanya; Howe, David A.; Wei Wong, Chee

2013-04-01

62

BVI impulsive noise reduction by higher harmonic pitch control - Results of a scaled model rotor experiment in the DNW  

Microsoft Academic Search

Results are presented of a model rotor acoustics test performed to examine the benefit of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulsive noise. A dynamically scaled, four-bladed, rigid rotor model, a 40-percent replica of the B0-105 main rotor, was tested in the German Dutch Wind Tunnel. Noise characteristics and noise directivity patterns as well

Wolf R. Splettstoesser; Klaus-J. Schultz; Roland Kube; Thomas F. Brooks; Earl R. Booth Jr.; Georg Niesl; Olivier Streby

1991-01-01

63

Effect of High Frequency Noise Current Sources on Noise Figure for Sub-50nm Node MOSFETs  

NASA Astrophysics Data System (ADS)

The downscaling of CMOS technology has resulted in strong improvement in RF performance of bulk and SOI MOSFETs. In order to realize a low-noise RF circuit, a deeper understanding of the noise performance for MOSFETs is required. Thermal noise is the main noise source of the CMOS device for high frequency performance, and is dominated by the drain channel noise, induced gate noise, and their correlation noise. In this work, we measured the RF noise parameter (Fmin, Rn, ?opt) of 45nm node MOSFETs from 5 to 15GHz and extracted noise sources and noise coefficients P, R, and C by using an extended van der Ziel's model. We found, for the first time, that correlation coefficient C decreases from positive to negative values when the gate length is reduced continuously with the gate length of sub-100nm. We confirmed that Pucel's noise figure model, using noise coefficients P, R, and C, can be considered a good approximation even for sub-50nm MOSFETs. We also discussed a scaling effect of the noise coefficients, especially the correlation noise coefficient C on the minimum noise figure.

Shimomura, Hiroshi; Kakushima, Kuniyuki; Iwai, Hiroshi

64

Air Weaponry Noise Source Characterization Protocol.  

National Technical Information Service (NTIS)

The technical report consists of three main elements: (1) measurement of real, airborne weapon systems to characterize the noise data required for accurate modeling, including characterization of complex air- weaponry noise due to a combination of various...

B. Ikelheimer C. Hobbs M. Downing M. James

2008-01-01

65

Rotor blade-vortex interaction noise reduction and vibration using higher harmonic control  

NASA Astrophysics Data System (ADS)

The use of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) noise is examined by means of a rotor acoustic test. A dynamically scaled, four-bladed, articulated rotor model was tested in a heavy gas (Freon-12) medium. Acoustic and vibration measurements were made for a large range of matched flight conditions where prescribed (open loop) HHC pitch schedules were superimposed on the normal (baseline) collective and cyclic trim pitch. A novel sound power measurement technique was developed to take advantage of the reverberance in the hard walled tunnel. Quantitative sound power results are presented for a 4/rev (4P) collective pitch HHC. By comparing the results using 4P HHC to corresponding baseline (no HHC) conditions, significant midfrequency noise reductions of 5-6 dB are found for low-speed descent conditions where BVI is most intense. For other flight conditions, noise is found to increase with the use of HHC. LF loading noise, as well as fixed and rotating frame vibration levels, show increased levels.

Brooks, Thomas F.; Booth, Earl R., Jr.

1990-09-01

66

Teaching about photodetection noise sources in the laboratory  

NASA Astrophysics Data System (ADS)

We describe simple experiments that allow students to observe, identify, understand and measure different noise sources always present in photodetection systems: amplifier noise, thermal resistance noise (Johnson noise), and photon noise (shot-noise). With a suitable low noise amplifier and a commercial photodiode, students can verify the dependence of photon noise versus light level. This photon shot-noise is directly related to the quantum << nature >> of light and it has long been considered as a fundamental limitation of the optical photodetection systems. It is sometimes mistakenly described as due to the detector itself. We show that it is possible, with fairly affordable laboratory teaching equipment, to measure a photocurrent with a noise power below the shot-noise level using a suitable light source. More precisely, using a photodiode and a high-quantum-efficiency light-emitting diode driven by a constant current source, we can observe a reduction of the photon noise power of about 0.8 dB below the shot-noise level.

Jacubowiez, Lionel; Roch, Jean F.; Poizat, Jean-Philippe; Grangier, Philippe

1997-12-01

67

Identification of noise sources based on experimental amplitude-frequency noise characteristics of aircraft  

Microsoft Academic Search

Problems involved in the identification of the principal sources of noise generation from experimentally obtained amplitude-frequency noise characteristics of aircraft on the ground and under flight conditions are examined. Particular attention is given to the analysis of sound interference and edge diffraction phenomena, which introduce noticeable distortions in the amplitude-frequency aircraft noise characteristics and make the task of identifying the

I. S. Zaguzov

1990-01-01

68

Wind turbines---low level noise sources interfering with restoration?  

Microsoft Academic Search

Wind turbines generate a low level noise and would thus not be expected to cause annoyance and disturb rest. In a society where people are being exposed to an increasing noise load, moderate and low level noise sources may also be perceived as annoying and hence inhibit restoration. This article presents an analysis of two socio-acoustic studies of wind turbine

Eja Pedersen; Kerstin Persson Waye

2008-01-01

69

Selective harmonic elimination in three-phase Current Source Inverter A generalized approach  

Microsoft Academic Search

This paper presents a generalized technique for realizing PWM patterns which provides selective harmonic elimination(SHE) for Current Source Inverters(CSI). The selective harmonic elimination method for CSI is generally based on independent chop angles between 0 and 30'. The conventional SHE method cannot handle more than a few harmonics as chop angles are always restricted to be in 0 and 30'.

P. Saranya; V. Rajini

2011-01-01

70

ACTIVE CONTROL OF A MOVING NOISE SOURCE—EFFECT OF OFF-AXIS SOURCE POSITION  

Microsoft Academic Search

An optimally arranged multiple-channel active-control system is known to be able to create a large quiet zone in free space for a stationary primary noise source. When the primary noise source moves, the active control of the noise becomes much more difficult, as the primary noise field changes with time in space. In this case, the controller of the control

J. Guo; J. PAN; M. HODGSON

2002-01-01

71

An integrated analog\\/digital random noise source  

Microsoft Academic Search

An integrated noise source (INS) has been fabricated in a standard 1.2 ?m digital CMOS technology. Wideband white noise is generated from the amplified thermal noise of large resistors, which in turn is coupled into a comparator to generate a random digital bit stream. The INS generates 100 mV rms of analog output noise over a bandwidth of 3.2 MHz

W. Timothy Holman; J. Alvin Connelly; Ahmad B. Dowlatabadi

1997-01-01

72

A Study for High-Order Harmonic Resonance Phenomena of Voltage Sourced Converter in Cable System  

Microsoft Academic Search

This paper presents high-order harmonic resonance phenomena of voltage sourced converter (VSC). When a voltage sourced converter is connected to power system with cables, there is possibility that minute high-order harmonic voltages of a voltage sourced converter are magnified by a series resonance and a parallel resonance, and high-order harmonic resonance phenomena are found by this study. The cause of

Tatsuhito Nakajima; Hirokazu Suzuki; Koji Temma; Isao Iyoda

2004-01-01

73

Radiated noise measurements from two unusual sources  

Microsoft Academic Search

As part of ongoing programs involving the measurement and assessment of ambient noise, data typical of two diverse but important environments have been acquired: (1) wide-band ambient noise in the neighborhood of deep-moored open-ocean buoys (typical of the NOAA 12-m discus buoys), and (2) wide-band noise generated by cycloidal propulsion systems (Voith-Schneider propellers). The extended use of the data buoys

P. Becker; E. Pence

1977-01-01

74

Noise from High Speed Maglev Systems: Noise Sources, Noise Criteria, Preliminary Design Guidelines for Noise Control, Recommendations for Acoustical Test Facility for Maglev Research.  

National Technical Information Service (NTIS)

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 sou...

C. E. Hanson P. Abbot I. Dyer

1993-01-01

75

Progress on Johnson noise thermometry using a quantum voltage noise source for calibration  

Microsoft Academic Search

We describe our progress toward a high-precision measurement of temperature using Johnson noise. Using a quantized voltage noise source (QVNS) based on the Josephson effect as a calculable noise source, we have been able to measure the ratio of the gallium and water triple-point temperatures to within an accuracy better than 100 ?K\\/K. We also describe the operation of our

Sae Woo Nam; Samuel P. Benz; Paul D. Dresselhaus; Charles J. Burroughs; Wes Tew; Rod White; John M. Martinis

2005-01-01

76

Continuous-variable quantum key distribution with Gaussian source noise  

SciTech Connect

Source noise affects the security of continuous-variable quantum key distribution (CV QKD) and is difficult to analyze. We propose a model to characterize Gaussian source noise through introducing a neutral party (Fred) who induces the noise with a general unitary transformation. Without knowing Fred's exact state, we derive the security bounds for both reverse and direct reconciliations and show that the bound for reverse reconciliation is tight.

Shen Yujie; Peng Xiang; Yang Jian; Guo Hong [CREAM Group, State Key Laboratory of Advanced Optical Communication Systems and Networks (Peking University) and Institute of Quantum Electronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)

2011-05-15

77

A low-noise high output impedance DC current source  

Microsoft Academic Search

The paper proposes a structure of a new low noise high output impedance DC current source which acts as a quasi-ideal source for frequencies lower than 10 kHz. It uses a feed-back structure with low noise operational amplifiers. The DC current, the small signal output impedance and the noise level are controlled by the value of one single resistance. The

J.-M. Routoure; D. Fadil; S. Flament; L. Méchin

2007-01-01

78

Harmony: EEG/MEG linear inverse source reconstruction in the anatomical basis of spherical harmonics.  

PubMed

EEG/MEG source localization based on a "distributed solution" is severely underdetermined, because the number of sources is much larger than the number of measurements. In particular, this makes the solution strongly affected by sensor noise. A new way to constrain the problem is presented. By using the anatomical basis of spherical harmonics (or spherical splines) instead of single dipoles the dimensionality of the inverse solution is greatly reduced without sacrificing the quality of the data fit. The smoothness of the resulting solution reduces the surface bias and scatter of the sources (incoherency) compared to the popular minimum-norm algorithms where single-dipole basis is used (MNE, depth-weighted MNE, dSPM, sLORETA, LORETA, IBF) and allows to efficiently reduce the effect of sensor noise. This approach, termed Harmony, performed well when applied to experimental data (two exemplars of early evoked potentials) and showed better localization precision and solution coherence than the other tested algorithms when applied to realistically simulated data. PMID:23071497

Petrov, Yury

2012-10-11

79

Harmony: EEG/MEG Linear Inverse Source Reconstruction in the Anatomical Basis of Spherical Harmonics  

PubMed Central

EEG/MEG source localization based on a “distributed solution” is severely underdetermined, because the number of sources is much larger than the number of measurements. In particular, this makes the solution strongly affected by sensor noise. A new way to constrain the problem is presented. By using the anatomical basis of spherical harmonics (or spherical splines) instead of single dipoles the dimensionality of the inverse solution is greatly reduced without sacrificing the quality of the data fit. The smoothness of the resulting solution reduces the surface bias and scatter of the sources (incoherency) compared to the popular minimum-norm algorithms where single-dipole basis is used (MNE, depth-weighted MNE, dSPM, sLORETA, LORETA, IBF) and allows to efficiently reduce the effect of sensor noise. This approach, termed Harmony, performed well when applied to experimental data (two exemplars of early evoked potentials) and showed better localization precision and solution coherence than the other tested algorithms when applied to realistically simulated data.

Petrov, Yury

2012-01-01

80

Compound noise analysis in digital circuits using blind source separation  

Microsoft Academic Search

In the past decade there have been significant efforts to analyze and solve signal integrity issues in pre-nanometer circuits. However, most of these techniques apply to single noise source, and cannot take into account the evolving reality of multiple noise sources interacting with each other. With the scaling of the technology into nanometer regime, maintaining historical rate of performance and

Vivek Nigam; Masud H. Chowdhury; Roland Priemer

2006-01-01

81

Consideration of some noise sources due to railway operation  

Microsoft Academic Search

A number of railway operation noise sources other than those leading to the far field (largely wheel\\/rail), train pass-by noise, are identified and briefly discussed. People primarily affected by these may include railway staff and passengers on the train, railway trackside staff, and wayside residents. Both environmental pollution and hearing protection may be involved. Sources considered include the following: close

C. G. Stanworth

1983-01-01

82

Radio Interference from Isolated Noise Sources on Overhead Transmission Lines  

Microsoft Academic Search

An isolated noise source such as a cracked insulator on a multiconductor overhead EHV transmission line produces an electric field adjacent to the line by two separate paths. One is the transmission of the noise voltage along the line causing a lateral field and the other is the direct radiation from the source acting as a dipole antenna. The theory

L. M. Wedepohl; J. N. Saha

1971-01-01

83

Ambiguity surface manifestation of downslope converted noise sources  

Microsoft Academic Search

Deals with the manifestation of downslope converted continental shelf noise sources (primarily ships) in the matched-field processor (MFP) ambiguity surface. Of interest is how noise sources outside the range of interest leak into the ambiguity surface through the sidelobe structure of the effective MFP beam (or cell) pattern. This study is carried out with simulations using the parabolic equation model.

Jean-Marie Q. D. Tran; W. S. Hodgkiss

1993-01-01

84

Initial results of a model rotor higher harmonic control (HHC) wind tunnel experiment on BVI impulsive noise reduction  

Microsoft Academic Search

Initial acoustic results are presented from a higher harmonic control (HHC) wind tunnel pilot experiment on helicopter rotor blade-vortex interaction (BVI) impulsive noise reduction, making use of the DFVLR 40-percent-scaled BO-105 research rotor in the DNW 6m by 8m closed test section. Considerable noise reduction (of several decibels) has been measured for particular HHC control settings, however, at the cost

W. R. Splettstoesser; G. Lehmann; B. van der Wall

1989-01-01

85

Global analysis of crisis in twin-well Duffing system under harmonic excitation in presence of noise  

Microsoft Academic Search

Evolution of a crisis in a twin-well Duffing system under a harmonic excitation in presence of noise is explored in detail by the generalized cell mapping with digraph (GCMD in short) method. System parameters are chosen in the range that there co-exist chaotic attractors and\\/or chaotic saddles, together with their evolution. Due to noise effects, chaotic attractors and chaotic saddles

Wei Xu; Qun He; Tong Fang; Haiwu Rong

2005-01-01

86

Response of Duffing system with delayed feedback control under combined harmonic and real noise excitations  

NASA Astrophysics Data System (ADS)

This paper presents a procedure for predicting the response of Duffing system with delayed feedback bang-bang control under combined harmonic and real noise excitations by using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged Itô stochastic differential equations for the system are derived by using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov (FPK) equation associated with the averaged Itô equations. It is shown that the time delay in feedback control can deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing system. The validity of the proposed method is confirmed by digital simulation.

Feng, C. S.; Wu, Y. J.; Zhu, W. Q.

2009-06-01

87

Clarification and Measurements of High Frequency Harmonic Resonance by a Voltage Sourced Converter  

Microsoft Academic Search

Summary form only given. This paper presents the clarification and measurements of a high-order harmonic resonance phenomenon for voltage sourced converters. When a voltage sourced converter is connected to a power system through a cable, there is a possibility that small, high frequency, harmonic voltages due to the converter are magnified by series and parallel resonances. The cause of the

K. Temma; F. Ishiguro; N. Toki; I. Iyoda; J. Paserba

2006-01-01

88

Simulation of Series Active and Passive Power Filter Combination System to Mitigate Current Source Harmonics  

NASA Astrophysics Data System (ADS)

This paper discusses a combination three phase system of series active power filter and passive power filter used to mitigate current source harmonics produced by a three phase diode rectifier with capacitive loads. A control method based on synchronous reference frame (SRF) is implemented to compensate for the current harmonics. Computer simulation and modelling of the combined filter system is carried out using Matlab/Simulink Power System Blockset (PSB) software. The single tuned passive power filters suppress 5th and 7th order current harmonics, while the series active power filter acts as a harmonic isolator between the source and load. Hence, the proposed system performs very well in mitigating source current harmonics to the level that comply the harmonic standard such as IEEE 519-1992.

Yusof, Yushaizad; Rahim, Nasrudin Abd.

2009-08-01

89

Heat conduction in disordered harmonic lattices with energy-conserving noise  

NASA Astrophysics Data System (ADS)

We study heat conduction in a harmonic crystal whose bulk dynamics is supplemented by random reversals (flips) of the velocity of each particle at a rate ?. The system is maintained in a nonequilibrium stationary state (NESS) by contacts with white-noise Langevin reservoirs at different temperatures. We show that the one-body and pair correlations in this system are the same (after an appropriate mapping of parameters) as those obtained for a model with self-consistent reservoirs. This is true both for the case of equal and random (quenched) masses. While the heat conductivity in the NESS of the ordered system is known explicitly, much less is known about the random mass case. Here we investigate the random system with velocity flips. We improve the bounds on the Green-Kubo conductivity obtained by Bernardin [J. Stat. Phys.JSTPBS0022-471510.1007/s10955-008-9620-1 133, 417 (2008)]. The conductivity of the one-dimensional system is then studied both numerically and analytically. This sheds some light on the effect of noise on the transport properties of systems with localized states caused by quenched disorder.

Dhar, Abhishek; Venkateshan, K.; Lebowitz, J. L.

2011-02-01

90

Development of Harmonic-Noise Reduction Technology in Diagnostic Method using AC Loss Current for Water Treed XLPE Cable  

NASA Astrophysics Data System (ADS)

Water tree is one of the degradation aspects of XLPE cables used for under-ground distribution or transmission lines. We have developed the loss current method using 3rd harmonic in AC loss current for cable diagnosis. Harmonic components in loss current arise as a result of the non-linear voltage-current characteristics of water trees. We confirmed that the 3rd harmonic in AC loss current had good correlation with water tree growth and break down strength. After that, we have applied this method to the actual 66kV XLPE cable lines. Up to now, the number of the application results is more than 120 lines. In this method, it is sometimes said that the degradation signal (3rd harmonic in loss current) is affected by the 3rd harmonic in the test voltage. To indicate and solve this problem, we investigated the extent of influence by 3rd harmonic in the test voltage, and found the rule of the influence. As a result, we developed a new technique of harmonic-noise reduction in loss current method that enabled a more highly accurate diagnosis and confirmed the effectiveness of this new technique by simulations and experiments with actual cables.

Tsujimoto, Tomiyuki; Nakade, Masahiko; Yagi, Yukihiro; Ishii, Noboru

91

Decomposition of noise sources of synchronous belt drives  

NASA Astrophysics Data System (ADS)

In this paper, the noise sources of synchronous belt are decomposed and formulated based on the analysis of the impact dynamics of belt-sprocket tooth interface. The impact/contact of belt-sprocket tooth and the vibration of belt span are modeled. The friction-vibrations interaction of belt tooth and the airflow-induced acoustic wave during belt-sprocket tooth engagement are comprehensively formulated. The structure-borne noise consists of structural impact noise and friction-induced noise. The airborne noise is due to airflow-induced acoustic wave during belt-sprocket tooth engaging. The spectral signatures of the varied noise are quantified, and the case studies are given to illustrate the influences of the tooth parameters and operation conditions on noise. The noise due to belt span vibration under impact ranges from hundreds to several thousand Hz. The impact noise, friction-induced noise and airflow-induced noise of belt tooth ranges from 3 kHz to 10 kHz.

Chen, Gang (Sheng); Zheng, Hui; Qatu, Mohamad

2013-04-01

92

Monitoring of environmental noise - noise source modeling for polish passenger trains  

Microsoft Academic Search

The study performed is a part of the project devoted to monitoring of environmental noise. The result of the IMAGINE noise source prediction model implementation based on reference data of that model is presented in this paper together with the main objectives of the realized study. The model implementation outcome is compared with the real-life measurement results and discrepancies between

M. Reiter; B. Kostek

2008-01-01

93

Initial results of a model rotor higher harmonic control (HHC) wind tunnel experiment on BVI impulsive noise reduction  

NASA Astrophysics Data System (ADS)

Initial acoustic results are presented from a higher harmonic control (HHC) wind tunnel pilot experiment on helicopter rotor blade-vortex interaction (BVI) impulsive noise reduction, making use of the DFVLR 40-percent-scaled BO-105 research rotor in the DNW 6m by 8m closed test section. Considerable noise reduction (of several decibels) has been measured for particular HHC control settings, however, at the cost of increased vibration levels and vice versa. The apparently adverse results for noise and vibration reduction by HHC are explained. At optimum pitch control settings for BVI noise reduction, rotor simulation results demonstrate that blade loading at the outer tip region is decreased, vortex strength and blade vortex miss-distance are increased, resulting altogether in reduced BVI noise generation. At optimum pitch control settings for vibration reduction adverse effects on blade loading, vortex strength and blade vortex miss-distance are found.

Splettstoesser, W. R.; Lehmann, G.; van der Wall, B.

1989-09-01

94

Harmonic Filters for Six-Phase and Other Multiphase Motors on Voltage Source Inverters  

Microsoft Academic Search

Inverter-driven motors having five, six, or more phases have smaller torque pulsations and lower rotor I2R loss due to harmonics than do their three-phase counterparts. However, they generally have higher stator harmonic currents. For example, six-phase motors, supplied by a six step voltage source inverters have fifth and seventh harmonic currents which are from two to five times as large

Eugene A. Klingshirn

1985-01-01

95

Suppress noise output of YIG-tuned sources  

NASA Astrophysics Data System (ADS)

The design of drive circuits aimed to reduce the noise output of YIG-tuned oscillators is presented. The noise reduction technique is illustrated by analysis of a low-noise electronically tunable oscillator in a spectrum analyzer. A variety of noise types (thermal, broadband operational amplifier, and popcorn noise) are evaluated, and measures to avoid the harmful constituents at each stage of the driver are indicated. It is mentioned that in a well-designed driver, operational amplifier noise is the limiting factor. Low-frequency drift as a source of signal variations is considered. Special attention is given to the driver's final stage design, noting the need to consider ground-potential drops resulting in the upset of the voltage/frequency relationships of earlier stages.

Bales, R.

1980-05-01

96

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  

NASA Astrophysics Data System (ADS)

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.

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

1993-01-01

97

Application of noise source identification techniques to information technology equipment  

NASA Astrophysics Data System (ADS)

Conventional noise source identification techniques are usually associated with larger mechanical sources such as engines, gearboxes, and the like, having medium to high noise emissions. The IT industry presents a different problem-set, though, in that the noise sources are usually smaller and are relatively low level. However, this does not prevent use of these techniques, in that they can be adapted to measurements on typical IT products. Tools for doing this include the use of non-contacting transducers such as laser vibrometers as references, making array measurements with a small-geometry transducer such as a probe microphone, and using conventional microphone arrays but with reduced grid spacing. This paper examines the application of these tools to noise source identification techniques such as coherent power, intensity mapping, and stationary and non-stationary near-field acoustical holography, such that they can be used on IT equipment. The different methods are illustrated with noise source identification exercises on a laptop PC and a 3 1/2-in. hard-disk-drive. Finally, the paper discusses the application of beam-forming techniques for noise source identification on IT products in general.

Upton, Roger; Dirks, Gijs

2005-09-01

98

IMAGINE Rail Noise Sources – A Practical Methodology  

Microsoft Academic Search

European Commission Directive 2002\\/49\\/EC requires that Common Assessment methods for the modelling of noise from road, rail,\\u000a aviation and industry shall be established by the Commission. The research project HARMONOISE was funded under the European\\u000a 5th Framework programme in order to commence this process. The research has been continued through the 6th Framework project IMAGINE to a point where the

M. Beuving; B. Hemsworth; R. Jones

99

Generalized techniques of selective harmonic elimination and current control in current source inverters\\/converters  

Microsoft Academic Search

This paper presents generalized techniques for realizing PWM patterns which provide selective harmonic elimination and current magnitude modulation (SHEM) for current source inverters\\/power converters (CSI\\/C). A combination of chops and short circuit pulses are positioned in such a way that lower order harmonics are eliminated selectively besides current magnitude modulation with minimum switching frequency. Generalized equations and tables which show

Hamid R. Karshenas; Hassan Ali Kojori; Shashi B. Dewan

1995-01-01

100

Covariance-based approaches to aeroacoustic noise source analysis.  

PubMed

In this paper, several covariance-based approaches are proposed for aeroacoustic noise source analysis under the assumptions of a single dominant source and all observers contaminated solely by uncorrelated noise. The Crame?r-Rao Bounds (CRB) of the unbiased source power estimates are also derived. The proposed methods are evaluated using both simulated data as well as data acquired from an airfoil trailing edge noise experiment in an open-jet aeroacoustic facility. The numerical examples show that the covariance-based algorithms significantly outperform an existing least-squares approach and provide accurate power estimates even under low signal-to-noise ratio (SNR) conditions. Furthermore, the mean-squared-errors (MSEs) of the so-obtained estimates are close to the corresponding CRB especially for a large number of data samples. The experimental results show that the power estimates of the proposed approaches are consistent with one another as long as the core analysis assumptions are obeyed. PMID:21110583

Du, Lin; Xu, Luzhou; Li, Jian; Guo, Bin; Stoica, Petre; Bahr, Chris; Cattafesta, Louis N

2010-11-01

101

MEG Source Localization Using Invariance of Noise Space  

PubMed Central

We propose INvariance of Noise (INN) space as a novel method for source localization of magnetoencephalography (MEG) data. The method is based on the fact that modulations of source strengths across time change the energy in signal subspace but leave the noise subspace invariant. We compare INN with classical MUSIC, RAP-MUSIC, and beamformer approaches using simulated data while varying signal-to-noise ratios as well as distance and temporal correlation between two sources. We also demonstrate the utility of INN with actual auditory evoked MEG responses in eight subjects. In all cases, INN performed well, especially when the sources were closely spaced, highly correlated, or one source was considerably stronger than the other.

Zhang, Junpeng; Raij, Tommi; Hamalainen, Matti; Yao, Dezhong

2013-01-01

102

MEG source localization using invariance of noise space.  

PubMed

We propose INvariance of Noise (INN) space as a novel method for source localization of magnetoencephalography (MEG) data. The method is based on the fact that modulations of source strengths across time change the energy in signal subspace but leave the noise subspace invariant. We compare INN with classical MUSIC, RAP-MUSIC, and beamformer approaches using simulated data while varying signal-to-noise ratios as well as distance and temporal correlation between two sources. We also demonstrate the utility of INN with actual auditory evoked MEG responses in eight subjects. In all cases, INN performed well, especially when the sources were closely spaced, highly correlated, or one source was considerably stronger than the other. PMID:23505502

Zhang, Junpeng; Raij, Tommi; Hämäläinen, Matti; Yao, Dezhong

2013-03-07

103

Wind turbines—low level noise sources interfering with restoration?  

NASA Astrophysics Data System (ADS)

Wind turbines generate a low level noise and would thus not be expected to cause annoyance and disturb rest. In a society where people are being exposed to an increasing noise load, moderate and low level noise sources may also be perceived as annoying and hence inhibit restoration. This article presents an analysis of two socio-acoustic studies of wind turbine noise with the emphasis on perception, annoyance and consequences for restoration. It is hypothesized that low and moderate stressors such as wind turbine noise could have an impact on health. The risk seems to be higher if restoration is, or is perceived to be, impaired and also for certain groups of individuals. The observations warrant further studies.

Pedersen, Eja; Persson Waye, Kerstin

2008-01-01

104

A high-flux high-order harmonic source  

NASA Astrophysics Data System (ADS)

We develop and implement an experimental strategy for the generation of high-energy high-order harmonics (HHG) in gases for studies of nonlinear processes in the soft x-ray region. We generate high-order harmonics by focusing a high energy Ti:Sapphire laser into a gas cell filled with argon or neon. The energy per pulse is optimized by an automated control of the multiple parameters that influence the generation process. This optimization procedure allows us to obtain energies per pulse and harmonic order as high as 200 nJ in argon and 20 nJ in neon, with good spatial properties, using a loose focusing geometry (f#~400) and a 20 mm long medium. We also theoretically examine the macroscopic conditions for absorption-limited conversion efficiency and optimization of the HHG pulse energy for high-energy laser systems.

Rudawski, P.; Heyl, C. M.; Brizuela, F.; Schwenke, J.; Persson, A.; Mansten, E.; Rakowski, R.; Rading, L.; Campi, F.; Kim, B.; Johnsson, P.; L'Huillier, A.

2013-07-01

105

A high-flux high-order harmonic source.  

PubMed

We develop and implement an experimental strategy for the generation of high-energy high-order harmonics (HHG) in gases for studies of nonlinear processes in the soft x-ray region. We generate high-order harmonics by focusing a high energy Ti:Sapphire laser into a gas cell filled with argon or neon. The energy per pulse is optimized by an automated control of the multiple parameters that influence the generation process. This optimization procedure allows us to obtain energies per pulse and harmonic order as high as 200 nJ in argon and 20 nJ in neon, with good spatial properties, using a loose focusing geometry (f#?400) and a 20 mm long medium. We also theoretically examine the macroscopic conditions for absorption-limited conversion efficiency and optimization of the HHG pulse energy for high-energy laser systems. PMID:23902040

Rudawski, P; Heyl, C M; Brizuela, F; Schwenke, J; Persson, A; Mansten, E; Rakowski, R; Rading, L; Campi, F; Kim, B; Johnsson, P; L'huillier, A

2013-07-01

106

DCT-Based Amplitude and Frequency Modulated Harmonic-Plus-Noise Modelling for Text-to-Speech Synthesis  

Microsoft Academic Search

We present a harmonic-plus-noise modelling (HNM) strategy in the context of corpus-based text-to-speech (TTS) synthesis, in which whole speech phonemes are modelled in their integrity, contrary to the traditional frame-based approach. The pitch and amplitude trajectories of each phoneme are modelled with a low-order DCT expansion. The parameter analysis algorithm is to a large extent aided and guided by the

K. Hermus; H. Van Hamme; W. Verhelst; S. Irhimeh; J. De Moortel

2007-01-01

107

Improved perception of speech in noise and Mandarin tones with acoustic simulations of harmonic coding for cochlear implantsa  

PubMed Central

Harmonic and temporal fine structure (TFS) information are important cues for speech perception in noise and music perception. However, due to the inherently coarse spectral and temporal resolution in electric hearing, the question of how to deliver harmonic and TFS information to cochlear implant (CI) users remains unresolved. A harmonic-single-sideband-encoder [(HSSE); Nie et al. (2008). Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing; Lie et al., (2010). Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing] strategy has been proposed that explicitly tracks the harmonics in speech and transforms them into modulators conveying both amplitude modulation and fundamental frequency information. For unvoiced speech, HSSE transforms the TFS into a slowly varying yet still noise-like signal. To investigate its potential, four- and eight-channel vocoder simulations of HSSE and the continuous-interleaved-sampling (CIS) strategy were implemented, respectively. Using these vocoders, five normal-hearing subjects’ speech recognition performance was evaluated under different masking conditions; another five normal-hearing subjects’ Mandarin tone identification performance was also evaluated. Additionally, the neural discharge patterns evoked by HSSE- and CIS-encoded Mandarin tone stimuli were simulated using an auditory nerve model. All subjects scored significantly higher with HSSE than with CIS vocoders. The modeling analysis demonstrated that HSSE can convey temporal pitch cues better than CIS. Overall, the results suggest that HSSE is a promising strategy to enhance speech perception with CIs.

Li, Xing; Nie, Kaibao; Imennov, Nikita S.; Won, Jong Ho; Drennan, Ward R.; Rubinstein, Jay T.; Atlas, Les E.

2012-01-01

108

Active noise control with linear control source and sensor arrays for a noise barrier  

Microsoft Academic Search

A study is conducted on minimizing the sum of the squared acoustic pressures with a linear array of control sources and a perpendicular linear array of error sensors, placed above the top of a noise barrier. Particular angular orientations, with respect to the center of the barrier top, and spacings of the linear arrays of control sources and error sensors

Carl R. Hart; Siu-Kit Lau

2012-01-01

109

Gaseous Discharge Super-High-Frequency Noise Sources  

Microsoft Academic Search

The positive column of an electrical discharge through argon it utilized as a source of random fluctuations to provide a standard noise source for microwave frequencies. It is shown that the waveguide may be matched to the discharge with very low reflection over the entire recommended transmission bandwidth of the waveguide without the utilization of tuned elements. Further, when the

Harwick Johnson; K. R. Deremer

1951-01-01

110

NOISECAM - USING BEAMFORMING TO IDENTIFY NOISE SOURCES ON HOVERCRAFT  

Microsoft Academic Search

Racing single seat hovercraft may be a fun thing to driv e but with a 2 stroke engine and a high revving industrial cooling fan they can be noisy. Identi fying the loudest sources on each craft quickly and easily is challenging because of the variety o f noise sources, and because each craft is different and mostly homemade. A

Keith Oakley

111

Blind Source Separation for Overcomplete Mixtures with Noise  

Microsoft Academic Search

Blind Source Separation (BSS) algorithms based on Independent Component Analysis (ICA) generally make several standard assumptions in ICA. The number of sources is assumed to be equal to the number of sensors and the presence of noise is negligible or Gaussian. However, these assumptions do not always hold in certain applications and may result in less than optimum performance from

L. C. KHOR; W. L. WOO; S. S. DLAY

112

Investigation of noise sources in SQUID electronics  

SciTech Connect

The performance of SQUID-based electronics outside a laboratory-controlled environment may be degraded from that found in laboratory operation. Investigations on superconducting tubes, wires, and sheets have been conducted to identify contributions to such noise. Results have been obtained for bulk and thin film samples utilizing both the conventional low temperature materials, as well as the new high temperature oxide materials. Experiments have been conducted to quantify flux redistribution and flux motion in superconducting samples subjected to temperature changes, temperature gradients, and magnetic field gradients. These investigations have been conducted at magnetic fields typical of many SQUID applications, with field intensities much smaller than the critical values H/sub cl/. Penetration depth effects, flux pinning effects, and flux motion effects have been observed. The various types of experiments conducted along with specific results are described.

Clem, T.R.; Goldstein, M.J.; Purpura, J.W.; Allen, L.H.; Claassen, J.H.; Gubser, D.U.; Wolf, S.A.

1989-03-01

113

Some remarks on source coherence affecting jet noise  

NASA Astrophysics Data System (ADS)

Literature on integral coherence length scales derived from cross spectral densities of jet noise is reviewed. Suggestions that coherent structures do not radiate sound significantly are criticized, since sound power measured experimentally consists of contributions from the excited sound field and from flow radiated sound. Theory shows that by increasing axial source coherence the radiated sound power can be strongly reduced at subsonic jet Mach numbers. The influence of azimuthal source coherence on the sound field radiated by a monopole source was investigated theoretically. Power spectral density and axisymmetric content increase significantly with increasing source coherence. If the dominating source term of shear noise for theta = 70 deg, which is proportional to the radial mean velocity, is introduced into the model, the least coherent source radiates most intensely. A strong second azimuthal sound component is present in the far field unless the source is very strongly coherent.

Michalke, A.

114

BVI impulsive noise reduction by higher harmonic pitch control - Results of a scaled model rotor experiment in the DNW  

NASA Astrophysics Data System (ADS)

Results are presented of a model rotor acoustics test performed to examine the benefit of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulsive noise. A dynamically scaled, four-bladed, rigid rotor model, a 40-percent replica of the B0-105 main rotor, was tested in the German Dutch Wind Tunnel. Noise characteristics and noise directivity patterns as well as vibratory loads were measured and used to demonstrate the changes when different HHC schedules were applied. Dramatic changes of the acoustic signatures and the noise radiation directivity with the HHC phase variations are found. Compared to the baseline conditions (without HHC), significant mid-frequency noise reductions of locally 6 dB are obtained for low-speed descent conditions where GVI is most intense. For other rotor operating conditions with less intense BVI there is less or no benefit from the use of HHC. LF noise and vibratory loads, especially at optimum noise reduction control settings, are found to increase.

Splettstoesser, Wolf R.; Schultz, Klaus-J.; Kube, Roland; Brooks, Thomas F.; Booth, Earl R., Jr.; Niesl, Georg; Streby, Olivier

1991-09-01

115

Johnson-noise thermometry based on a quantized-voltage noise source at NIST  

NASA Astrophysics Data System (ADS)

Johnson Noise Thermometry is an electronic approach to measuring temperature. For several years, NIST has been developing a switching-correlator-type Johnson-noise thermometer that uses a quantized voltage noise source as an accurate voltage reference. When this method is used to measure resistors at the triple-point of water, the system creates a direct electronic method for determining the ratio of the Boltzmann constant k to the Planck constant h. In 2010, NIST optimized the JNT system for use with 100 ? sense resistors and produced a determination for k with a relative standard uncertainty of 12×10-6. In order to further validate and improve the measurement method, we modified the system to operate with a 200 ? resistor source instead of the 100 ? source. In this paper, we summarize the technical challenges and achievements to date and project what is achievable in the near future.

Pollarolo, A.; Jeong, T.; Benz, S. P.; Dresselhaus, P. D.; Rogalla, H.; Tew, W. L.

2013-09-01

116

Determining the influence of age and diabetes on the second-harmonic generation strength of dermal collagen fibers in vivo by using electronic noises  

NASA Astrophysics Data System (ADS)

It is commonly believed that intrinsic skin aging is associated with the change of the collagen structures. The influence of the diabetes on the skin collagen is also considered to be similar to aging. Moreover, second-harmonic-generation (SHG) in collagen fibers is known to reflect the detailed collagen structures. It is thus highly valuable to adopt the SHG intensity as a collagen structure indicator. With the help of SHG, recently one can achieve in vivo imaging which provides the information of what really happens beneath the human skin. However, when analyzing the images, the SHG brightness of each pixel highly depends on the illumination condition, the depth of the SHG source, and the voltage of PMT. Therefore, it is important to calibrate these factors before statistical analysis. In this paper, we present our recent development that calibrates the in vivo SHG images by using noises. We first determine the regions of signals and noises by setting a threshold relating to the standard deviation of the image. By using the assumption that the noise was amplified by PMT with an amplification ratio the same as the SHG signal, we can define the brightness of the noise region as a parameter representing the voltage of PMT, and use this parameter to calibrate all SHG images. After calibrating, we can then compare different images from volunteers and analyze the influence of aging and diabetes on the SHG intensity from collagen fibers, even if the voltage of PMT was not fixed.

Hung, Wei-Chun; Sun, Chi-Kuang; Chen, Argon

2013-02-01

117

Noise tube sources for the far IR and millimeter region.  

PubMed

The radiant output of a noise tube (C. P. Clare Model TN-167), designed for the 90-140-GHz (3.3-2.1-mm) frequency range, has been compared with that from mercury lamps over the wavelength region from 0.4 to ~6 mm. Lamellar grating and Michelson Fourier transform spectrometers were used in conjunction with He cooled bolometers of NEP from 10(-12) to 10(-14) W/(H(2))(1/2) to measure relative spectral irradiance. With this instrumental arrangement, the radiant power emitted by the noise tube was observed to be less than that from a mercury lamp, at least to a 3-mm wavelength, but it produced less source noise than an ac operated mercury lamp. When the noise tube operating current was reduced, the spectral irradiance peak shifted to longer wavelengths. PMID:20531709

Möller, K D; Zoeller, R G; Ugras, N G; Zabiocky, P; Heaney, J B; Stewart, K P; Boucarut, R A

1988-05-15

118

Review of Subcritical Source-Driven Noise Analysis Measurements  

SciTech Connect

Subcritical source-driven noise measurements are simultaneous Rossi-{alpha} and randomly pulsed neutron measurements that provide measured quantities that can be related to the subcritical neutron multiplication factor. In fact, subcritical source-driven noise measurements should be performed in lieu of Rossi-{alpha} measurements because of the additional information that is obtained from noise measurements such as the spectral ratio and the coherence functions. The basic understanding of source-driven noise analysis measurements can be developed from a point reactor kinetics model to demonstrate how the measured quantities relate to the subcritical neutron multiplication factor. More elaborate models can also be developed using a generalized stochastic model. These measurements can be simulated using Monte Carlo codes to determine the subcritical neutron multiplication factor or to determine the sensitivity of calculations to nuclear cross section data. The interpretation of the measurement using a Monte Carlo method is based on a perturbation model for the relationship between the spectral ratio and the subcritical neutron multiplication factor. The subcritical source-driven noise measurement has advantages over other subcritical measurement methods in that reference measurements at delayed critical are not required for interpreting the measurements. Therefore, benchmark or in-situ subcritical measurements can be performed outside a critical experiment facility. Furthermore, a certain ratio of frequency spectra has been shown to be independent of detection efficiency thereby making the measurement more robust and unaffected by drifts or changes in instrumentation during the measurement. Criteria have been defined for application of this measurement method for benchmarks and in-situ subcritical measurements. An extension of the source-driven subcritical noise measurement has also been discussed that eliminates the few technical challenges for in-situ applications.

Valentine, T.E.

1999-11-24

119

Recent developments in noise research at Deutsche Bahn (noise assessment, noise source localization and specially monitored track)  

NASA Astrophysics Data System (ADS)

To strengthen the environmental friendliness of railway traffic in Germany, Deutsche Bahn (DB) is in the process of performing a major research programme concerning noise reduction. To realize this, the DB `Low Noise Railway' programme deals simultaneously with the noise treatment of trains and the wheel/rail system as well as other topics. The assessment of a particular sound experience as annoying noise is a very personal judgement and cannot be dealt with by physical quantities alone. To permit a better understanding of this phenomenon and to support the legislative authorities, the assessment of noise quality is being investigated in detail. To reduce railway noise, the exact location and the magnitude of the different sound sources have to be known. This can be analyzed with an array of many microphones which has been developed by DB in the last few years. Most recently, DB has developed the acoustic concept of the `Specially Monitored Track (SMT)' into a practical application and is now starting to upgrade SMT to increased performance and at a lower cost.

Schulte-Werning, B.; Jäger, K.; Strube, R.; Willenbrink, L.

2003-10-01

120

Theory of the fission source driven neutron noise field  

SciTech Connect

The extensive use of the /sup 252/Cf driven noise technique makes it desirable to develop a general theory of the fission source driven noise field. For photoneutron sources and a point reactor model, a unified theory of the different experimental techniques used in noise analysis was developed by Pacilio. They used the probability generating function (PGF) as the common element of all the experimental techniques. Similarly, if the PGF is obtained in the presence of a fission source, the equations relevant to all the noise techniques using such a source can be obtained. A very detailed theory has been proposed recently in order to include the space and energy variables in the equations describing the stochastic field for both types of sources. The complications of the formalism restrict its practical applications to the calculation of the first moments of the distribution of counts instead of the calculation of the PGF. Consequently it seems convenient to explore the possibility of obtaining the entire PGF with a simpler model.

Difilippo, F.C.

1984-01-01

121

Implications of Noise Source Resolution on Detection Performance for Horizontal Directional Systems Operating in Ship-Induced Noise Fields.  

National Technical Information Service (NTIS)

This report develops relationships between the probability of detection and the system and environmental factors governing the extent to which individual noise sources are angularly resolved by a linear array operating in a ship-induced noise field. The e...

R. M. Heitmeyer L. J. Davis N. Yen

1985-01-01

122

Investigation of jet-installation noise sources under static conditions  

NASA Astrophysics Data System (ADS)

The acoustical effects of operating a 6-cm exit-diameter nozzle in the presence of a wing-flap model under static conditions are examined experimentally. The geometric parameters of the wing-flap model are chosen to represent a realistic jet-engine installation on a wide-body midrange transport airplane. The effects of varying the installation parameters and the noise sources associated with the engine-installation effects are discussed. The major noise sources are the flow interaction of the jet and wing undersurface, the flow interaction of the jet with the side edges of the flap cutout and flap trailing edge, and the reflection of the jet noise off the undersurface of the wing and flap.

Shearin, J. G.

1983-08-01

123

The Effect of Harmonic Currents on the Noise of a Three-Phase Induction Motor  

Microsoft Academic Search

The magnetic air gap radial force waves in a three-phase induction motor excited with a nonsinusoidal supply from a solid-state converter are investigated analytically, taking into account the interaction between the flux density waves due to the harmonic currents. A simple method for the prediction of the frequencies and origins of the magnetic force components paused by the harmonic currents

S. J. Yang; P. L. Timar

1980-01-01

124

Identification of complex diesel engine noise sources based on coherent power spectrum analysis  

NASA Astrophysics Data System (ADS)

This paper presents an identification of complex diesel engine noise sources based on coherent power spectrum analysis. Noise sources identification is essential for making noise reduction strategies. The author adopts methods of hierarchy diagnosis together with coherent power spectrum analysis to identify complex noise sources of diesel engine. In investigation of the noise sources, the hierarchy tree and judgment matrix are given. Through noise sources identification, the main part of radiating surface noise is found. The result shows that the noise of low-frequency belt is mainly machinery noise from oil pump, gear and valve mechanism, etc., and it is radiated mostly from thin-walled part like gear cover and valve cover etc., while the noise of high-frequency belt is mainly combustion noise and oil pan is identified as the main part of noise reduction.

Shu, Gequn; Liang, Xingyu

2007-01-01

125

Modeling spatiotemporal noise covariance for MEG\\/EEG source analysis  

Microsoft Academic Search

We propose a new model for approximating spatiotemporal noise covariance for use in MEG\\/EEG source analysis. Our model is an extension of an existing model [1,2] that uses a single Kronecker product of a pair of matrices - temporal and spatial covariance; we employ a series of Kronecker products in order to construct a better approximation of the full covariance.

S. M. Plis; J. S. George; S. C. Jun; J. Pare-Blagoev; D. M. Ranken; D. M. Schmidt; C. C. Wood

2005-01-01

126

Screech Noise Source Structure of a Supersonic Rectangular Jet.  

National Technical Information Service (NTIS)

The near-field of the screech noise source structure of an under-expanded supersonic rectangular jet was studied in detail. A miniature probe microphone was used along with a reference microphone to determine the amplitude and phase of the sound pressure ...

E. J. Rice R. Taghavi

1992-01-01

127

The modelling of ambient noise due to shipping and wind sources in complex environments  

Microsoft Academic Search

A review of noise modelling techniques is given for shipping and wind noise sources covering the frequency range 50 Hz to 3 kHz and concentrating mainly on work done from 1980 onwards. Propagation mechanisms, sources of input data and a variety of established noise models for both noise sources are described and results presented in terms of horizontal and vertical

R. M. Hamson

1997-01-01

128

Identification and classification of noise sources in a chain conveyor  

NASA Astrophysics Data System (ADS)

Noise induced hearing loss (NIHL) is one of the most significant disabilities of workers in the mining industry. In response, the National Institute of Occupational Safety and Health (NIOSH) is conducting a study associated with mining equipment. This study outlines the analysis of a chain conveyor. Band-limited accelerometer, sound-intensity, far-field and near-field microphone measurements were taken along the conveyor section. The sound intensity measurements were used to identify areas with high noise as well as to calculate and 1/3-octave sound power levels. The total sound power results were used to classify the dominant noise sources where the 1/3-octave sound power results were used to identify the most contributive frequency bands to the overall noise of the system. Coherence analysis was performed between accelerometer and microphone measurements to identify structure-borne and air-borne noise paths of the system. Summary results from the analysis include recommendations for transmission control and damping devices and their ability to reduce noise to regulatory acceptable levels.

Homer, John P.; Vipperman, Jeffrey S.; Reeves, Efrem R.

2002-05-01

129

A high intensity acoustic source for active attenuation of exhaust noise  

NASA Astrophysics Data System (ADS)

An electropneumatic sound source was developed for active noise control systems applied in hostile environments such as the exhaust systems of gas turbines and internal combustion engines. It employs a gas bearing to support the friction free motion of a sliding plate which is used to modulate the supply of compressed air. The sliding plate is driven by an electrodynamic vibrator. Experimental results demonstrate that this arrangement reduces harmonic distortion to at least 20 dB below the fundamental driving frequency for most operating conditions. A theoretical analysis of the transducer enables predictions to be made of the acoustic volume velocity (source strength) produced by the transducer as a function of the upstream pressure and displacement of the sliding valve. Applicability of the transducer to gas turbine and internal combustion engine exhaust systems was tested, and net power consumption resulting from the operation of the device was estimated.

Glendinning, A. G.; Elliott, S. J.; Nelson, P. A.

1988-04-01

130

Temporal Coherence Effects on Coherent Diffractive Imaging of a Binary Sample by a High Harmonic Source  

NASA Astrophysics Data System (ADS)

Coherent Diffractive Imaging (CDI) is performed with single and multiple harmonics from an ultrafast HHG source. The effect of HHG source bandwidth on the effectiveness of the reconstruction algorithms is compared. A low quality reconstruction from broadband data is achieved assuming full coherence in the algorithm.

Parsons, A. D.; Chapman, R. T.; Mills, B.; Bajt, S.; Frey, J. G.; Brocklesby, W. S.

2013-03-01

131

Identification and Proposed Control of Helicopter Transmission Noise at the Source.  

National Technical Information Service (NTIS)

Helicopter cabin interiors require noise treatment which is expensive and adds weight. The gears inside the main power transmission are major sources of cabin noise. Work conducted by the NASA Lewis Research Center in measuring cabin interior noise and in...

J. J. Coy R. F. Handschuh D. G. Lewicki R. G. Huff E. A. Krejsa

1988-01-01

132

Identification and Proposed Control of Helicopter Transmission Noise at the Source.  

National Technical Information Service (NTIS)

Helicopter cabin interiors require noise treatment which is expensive and adds weight. The gears inside the main power transmission are major sources of cabin noise. Work conducted by the NASA Lewis Research Center in measuring cabin interior noise and in...

J. J. Coy R. F. Handschuh D. G. Lewicki R. G. Huff E. A. Krejsa

1987-01-01

133

The influence of noise sources on cross-correlation amplitudes  

NASA Astrophysics Data System (ADS)

We use analytical examples and asymptotic forms to examine the mathematical structure and physical meaning of the seismic cross-correlation measurement. We show that in general, cross correlations are not Green's functions of medium, and may be very different depending on the source distribution. The modelling of noise sources using spatial distributions as opposed to discrete collections of sources is emphasized. When stations are illuminated by spatially complex source distributions, cross correlations show arrivals at a variety of time lags, from zero to the maximum surface-wave arrival time. Here, we demonstrate the possibility of inverting for the source distribution using the energy of the full cross-correlation waveform. The interplay between the source distribution and wave attenuation in determining the functional dependence of cross-correlation energies on station-pair distance is quantified. Without question, energies contain information about wave attenuation. However, the accurate interpretation of such measurements is tightly connected to the knowledge of the source distribution.

Hanasoge, Shravan M.

2013-01-01

134

Noise squeezing and commutation relations in quantum-non-demolition quasistroboscopic schemes for coupled harmonic oscillators  

Microsoft Academic Search

Quantum-non-demolition measurement strategies have been studied for two coupled harmonic oscillators. An estimate for the squeezing factor in a quasistroboscopic measurement scheme has been obtained starting from the Heisenberg uncertainty principle and the commutation relation.

Alessandro Rioli; Ubaldo Tambini

1994-01-01

135

Measurements of nonlinear harmonic generation at the Advanced Photon Source's SASE FEL  

SciTech Connect

SASE saturation was recently achieved at the Advanced Photon Source's SASE FEL in the low-energy undulator test line (LEUTL) at 530 nm and 385 nm. The electron beam microbunching becomes more and more prominent until saturation is achieved. This bunching causes nonlinear harmonic emission that extends the usefulness of a SASE system in achieving shorter FEL wavelengths for the same electron beam energy. They have investigated the intensity of the fundamental and second-harmonic undulator radiation as a function of distance along the undulator line and present the experimental results and compare them to numerical simulations. In addition, they have measured the single-shot second harmonic spectra as well as the simultaneous fundamental and second harmonic spectra and present the experimental results.

Biedron, S.G.; Dejus, E.J.; Huang, Z.; Milton, S.V.; Sajaev, V.; Berg, W.; Borland, M.; Den Hartog, P.K.; Erdmann, M.; Fawley, W.M.; Gluskin, E.; Kim, K.-J.; Lewellen, J.W.; Li, Y.; Moog, E.R.; Nassiri, A.; Wiermerslage, G.; Yang, B.X.

2002-03-01

136

An investigation of rotor harmonic noise by the use of small scale wind tunnel models  

NASA Astrophysics Data System (ADS)

Noise measurements of small scale helicopter rotor models were compared with noise measurements of full scale helicopters to determine what information about the full scale helicopters could be derived from noise measurements of small scale helicopter models. Comparisons were made of the discrete frequency (rotational) noise for 4 pairs of tests. Areas covered were tip speed effects, isolated rotor, tandem rotor, and main rotor/tail rotor interaction. Results show good comparison of noise trends with configuration and test condition changes, and good comparison of absolute noise measurements with the corrections used except for the isolated rotor case. Noise measurements of the isolated rotor show a great deal of scatter reflecting the fact that the rotor in hover is basically unstable.

Sternfeld, H., Jr.; Schaffer, E. G.

1982-04-01

137

Volcanic jet noise: infrasonic source processes and atmospheric propagation  

NASA Astrophysics Data System (ADS)

Volcanic eruption columns are complex flows consisting of (possibly supersonic) injections of ash-gas mixtures into the atmosphere. A volcanic eruption column can be modeled as a lower momentum-driven jet (the gas-thrust region), which transitions with altitude into a thermally buoyant plume. Matoza et al. [2009] proposed that broadband infrasonic signals recorded during this type of volcanic activity represent a low-frequency form of jet noise. Jet noise is produced at higher acoustic frequencies by smaller-scale man-made jet flows (e.g., turbulent jet flow from jet engines and rockets). Jet noise generation processes could operate at larger spatial scales and produce infrasonic frequencies in the lower gas-thrust portion of the eruption column. Jet-noise-like infrasonic signals have been observed at ranges of tens to thousands of kilometers from sustained volcanic explosions at Mount St. Helens, WA; Tungurahua, Ecuador; Redoubt, AK; and Sarychev Peak, Kuril Islands. Over such distances, the atmosphere cannot be considered homogeneous. Long-range infrasound propagation takes place primarily in waveguides formed by vertical gradients in temperature and horizontal winds, and exhibits strong spatiotemporal variability. The timing and location of volcanic explosions can be estimated from remote infrasonic data and could be used with ash cloud dispersion forecasts for hazard mitigation. Source studies of infrasonic volcanic jet noise, coupled with infrasound propagation modeling, hold promise for being able to constrain more detailed eruption jet parameters with remote, ground-based geophysical data. Here we present recent work on the generation and propagation of volcanic jet noise. Matoza, R. S., D. Fee, M. A. Garcés, J. M. Seiner, P. A. Ramón, and M. A. H. Hedlin (2009), Infrasonic jet noise from volcanic eruptions, Geophys. Res. Lett., 36, L08303, doi:10.1029/2008GL036486.

Matoza, R. S.; Fee, D.; Ogden, D. E.

2011-12-01

138

Quantifying multiscale noise sources in single-molecule time series  

PubMed Central

When analyzing single-molecule data, a low-dimensional set of system observables typically serve as the observational data. We calibrate stochastic dynamical models from time series that record such observables (our focus throughout is on a molecule’s end-to-end distance). Numerical techniques for quantifying noise from multiple time scales in a single trajectory, including experimental instrument and inherent thermal noise, are demonstrated. The techniques are applied to study time series coming from both simulations and experiments associated with the nonequilibrium mechanical unfolding of titin’s I27 domain. The estimated models can be used for several purposes: (1) detect dynamical signatures of “rare events” by analyzing the effective diffusion and force as a function of the monitored observable; (2) quantify the influence that experimentally unobservable conformational degrees of freedom have on the dynamics of the monitored observable; (3) quantitatively compare the inherent thermal noise to other noise sources, e.g. instrument noise, variation induced by conformational heterogeneity, etc.; (4) simulate random quantities associated with repeated experiments; (5) apply pathwise (i.e. trajectory-wise) hypothesis tests to assess the goodness-of-fit of models and even detect conformational transitions in noisy signals. These items are all illustrated with several examples.

Calderon, Christopher P.; Harris, Nolan C.; Kiang, Ching-Hwa; Cox, Dennis D.

2009-01-01

139

Sources, control, and effects of noise from aircraft propellers and rotors  

Microsoft Academic Search

Recent NASA and NASA sponsored research on the prediction and control of propeller and rotor source noise, on the analysis and design of fuselage sidewall noise control treatments, and on the measurement and quantification of the response of passengers to aircraft noise is described. Source noise predictions are compared with measurements for conventional low speed propellers, for new high speed

J. S. Mixson; G. C. Greene; T. K. Dempsey

1981-01-01

140

Ultrahigh supermode noise suppressing ratio of a semiconductor optical amplifier filtered harmonically mode-locked Erbium-doped fiber laser.  

PubMed

The supermode noise suppressing ratio (SMSR) and the phase noise of a harmonically mode-locked Erbium-doped fiber laser (HML-EDFL) with an intra-cavity semiconductor optical amplifier (SOA) and an optical band-pass filter (OBPF) are improved and compared with a state-of-the-art Fabry-Perot laser diode (FPLD) injection-mode-locked EDFL. By driving the intra-cavity SOA based high-pass filter at unitary gain condition, the SMSR of the HML-EDFL is enhanced to 82 dB at the cost of degrading phase noise, increasing jitter, and broadened pulse width. The adding of OBPF further improves the SMSR, pulse width, phase noise, and jitter of the SOA-filtered HML-EDFL to 90 dB, 42 ps, -112 dBc/Hz, and 0.7 ps, respectively. The ultrahigh SMSR of the SOA-filtered HML-EDFL can compete with that of the FPLD injection-mode-locked EDFL without sacrificing its pulse width and jitter performances. PMID:19498744

Lin, Gong-Ru; Wu, Ming-Chung; Chang, Yung-Cheng; Pan, Ci-Ling

2005-09-01

141

Ultrahigh supermode noise suppressing ratio of a semiconductor optical amplifier filtered harmonically mode-locked Erbium-doped fiber laser  

NASA Astrophysics Data System (ADS)

The supermode noise suppressing ratio (SMSR) and the phase noise of a harmonically mode-locked Erbium-doped fiber laser (HML-EDFL) with an intra-cavity semiconductor optical amplifier (SOA) and an optical band-pass filter (OBPF) are improved and compared with a state-of-the-art Fabry-Perot laser diode (FPLD) injection-mode-locked EDFL. By driving the intra-cavity SOA based high-pass filter at unitary gain condition, the SMSR of the HML-EDFL is enhanced to 82 dB at the cost of degrading phase noise, increasing jitter, and broadened pulse width. The adding of OBPF further improves the SMSR, pulse width, phase noise, and jitter of the SOA-filtered HML-EDFL to 90 dB, 42 ps, -112 dBc/Hz, and 0.7 ps, respectively. The ultrahigh SMSR of the SOA-filtered HML-EDFL can compete with that of the FPLD injection-mode-locked EDFL without sacrificing its pulse width and jitter performances.

Lin, Gong-Ru; Wu, Ming-Chung; Chang, Yung-Cheng; Pan, Ci-Ling

2005-09-01

142

Modeling spatiotemporal noise covariance for MEG\\/EEG source analysis  

Microsoft Academic Search

We propose a new model for approximating spatiotemporal noise covariance for\\u000ause in MEG\\/EEG source analysis. Our model is an extension of an existing model\\u000a[1,2] that uses a single Kronecker product of a pair of matrices - temporal and\\u000aspatial covariance; we employ a series of Kronecker products in order to\\u000aconstruct a better approximation of the full covariance.

S. M. Plis; J. S. George; S. C. Jun; J. Pare-Blagoev; D. M. Ranken; D. M. Schmidt; C. C. Wood

2005-01-01

143

(252)Cf-source-driven neutron noise analysis method  

Microsoft Academic Search

The Cf-252-source-driven neutron noise analysis method has been tested in a wide variety of experiments that have indicated the broad range of applicability of the method. The neutron multiplication factor k(sub eff) has been satisfactorily determined for a variety of materials including uranium metal, light water reactor fuel pins, fissile solutions, fuel plates in water, and interacting cylinders. For a

J. T. Mihalczo; W. T. King; E. D. Blakeman

1985-01-01

144

Adaptive Selective Harmonic Minimization Based on ANNs for Cascade Multilevel Inverters With Varying DC Sources  

SciTech Connect

A new approach for modulation of an 11-level cascade multilevel inverter using selective harmonic elimination is presented in this paper. The dc sources feeding the multilevel inverter are considered to be varying in time, and the switching angles are adapted to the dc source variation. This method uses genetic algorithms to obtain switching angles offline for different dc source values. Then, artificial neural networks are used to determine the switching angles that correspond to the real-time values of the dc sources for each phase. This implies that each one of the dc sources of this topology can have different values at any time, but the output fundamental voltage will stay constant and the harmonic content will still meet the specifications. The modulating switching angles are updated at each cycle of the output fundamental voltage. This paper gives details on the method in addition to simulation and experimental results.

Filho, Faete [ORNL; Maia, Helder Z [UFMS, Department of Electrical Engineering; Mateus, Tiago Henrique D [ORNL; Ozpineci, Burak [ORNL; Tolbert, Leon M [ORNL; Pinto, Joao Onofre P [ORNL

2013-01-01

145

Tumbleweeds and airborne gravitational noise sources for LIGO  

NASA Astrophysics Data System (ADS)

The relative positions of the test masses in gravitational-wave detectors will be influenced not only by astrophysical gravitational waves, but also by the fluctuating Newtonian gravitational forces of moving masses in the ground and air around the detector. These effects are often referred to as gravity gradient noise. This paper considers the effects of gravity gradients from density perturbations in the atmosphere, and from massive airborne objects near the detector. These have been discussed previously by Saulson (1984 Phys. Rev. D 30 732), who considered the effects of background acoustic pressure waves and of massive objects moving smoothly past the interferometer; the gravity gradients he predicted would be too small to be of serious concern even for advanced interferometric gravitational-wave detectors. In this paper, I revisit these phenomena, considering transient atmospheric shocks, and estimating the effects of sound waves or objects colliding with the ground or buildings around the test masses. I also consider another source of atmospheric density fluctuations: temperature perturbations that are advected past the detector by the wind. I find that background acoustic noise and temperature fluctuations still produce gravity gradient noise that is below the noise floor even of advanced interferometric detectors, although temperature perturbations carried along non-laminar streamlines could produce noise that is within an order of magnitude of the projected noise floor at 10 Hz. A definitive study of this effect may require better models of the wind flow past a given instrument. I also find that transient shockwaves in the atmosphere could potentially produce large spurious signals, with signal-to-noise ratios in the hundreds in an advanced interferometric detector. These signals could be vetoed by means of acoustic sensors outside of the buildings. Massive wind-borne objects such as tumbleweeds could also produce gravity gradient signals with signal-to-noise ratios in the hundreds if they collide with the interferometer buildings, so it may be necessary to build fences preventing such objects from approaching within about 30 m of the test masses.

Creighton, Teviet

2008-06-01

146

Harmonic load\\/source pull strategies for high efficiency PAs design  

Microsoft Academic Search

An advanced load\\/source pull bench has been used in conjunction with harmonic tuning techniques for accurate and effective power amplifier design. The optimization strategy is presented together with the measured results obtained with a medium power 1-mm MESFET.

P. Colantonio; A. Ferrero; F. Giannini; E. Limiti; V. Teppati

2003-01-01

147

Voltage harmonic control of Z-source inverter for UPS applications  

Microsoft Academic Search

This paper presents a control method for obtaining sinusoidal output voltage regardless of the nonlinear and unbalanced loads. Control of the DC boost stage and capacitor voltage is presented. The resonant regulators are used for selective harmonic cancellation of the output AC voltage. The Z-source inverter is able to provide higher AC voltage related to the DC link voltage than

Arkadiusz Kulka; Tore Undeland

2008-01-01

148

Determination of noise source heights, part II: Measurement of the equivalent source height of highway vehicles  

NASA Astrophysics Data System (ADS)

This is the second of two companion papers which describe the measurement of the equivalent point source height on highway vehicles. The first paper describes the measurement method, and the second its application to highway vehicles. This paper discusses the measurements on moving highway vehicles. First it is shown how the measurement method is suitable for measuring the equivalent point source height for application to noise barrier design. The measurement of noise source height on 36 heavy trucks, 37 medium vehicles and 25 small vehicles are then described. The results give the equivalent point source height as a function of frequency for each type of vehicle and identify the contributions of engine noise and tire noise. The measured source height was found to be ~ 1.2 m for heavy vehicles, ~0.7 m for medium vehicles and ~0.6 m for small vehicles. These heights are significantly different from those currently used to design noise barriers, and suggest that further work should be undertaken to assess the implications of these results.

Glegg, S. A. L.; Yoon, J. R.

1990-11-01

149

Identification, modelling and reduction potential of railway noise sources: a critical survey  

NASA Astrophysics Data System (ADS)

Environmental requirements for railway operations will become tighter in the future. In particular, annoyance due to railway noise has to be taken carefully into account in the expansion of freight traffic as well as in new high speed line projects. Reduction of noise at source can be more attractive than the use of noise barriers but this requires a thorough understanding of the source mechanisms. This paper presents a critical survey of the identification and modelling of railway noise sources and summarizes the current knowledge of the physical source phenomena (mainly rolling and aerodynamic sources) as well as the potential for noise reduction. Future research perspectives are also given. These concern, in particular, improvements to source modelling, especially for aerodynamic noise, investigation of other sources and development of more advanced models for predicting railway noise in the environment. These should include a better description of the sources, obtained from modelling.

Talotte, C.; Gautier, P.-E.; Thompson, D. J.; Hanson, C.

2003-10-01

150

Maximum-likelihood detection of sources among Poissonian noise  

NASA Astrophysics Data System (ADS)

A maximum likelihood (ML) technique for detecting compact sources in images of the X-ray sky is examined. Such images, in the relatively low exposure regime accessible to present X-ray observatories, exhibit Poissonian noise at background flux levels. A variety of source detection methods are compared via Monte Carlo, and the ML detection method is shown to compare favourably with the optimized-linear-filter (OLF) method when applied to a single image. Where detection proceeds in parallel on several images made in different energy bands, the ML method is shown to have some practical advantages which make it superior to the OLF method. Some criticisms of ML are discussed. Finally, a practical method of estimating the sensitivity of ML detection is presented, and is shown to be also applicable to sliding-box source detection.

Stewart, I. M.

2009-03-01

151

Suppress noise output of YIG-tuned sources  

Microsoft Academic Search

The design of drive circuits aimed to reduce the noise output of YIG-tuned oscillators is presented. The noise reduction technique is illustrated by analysis of a low-noise electronically tunable oscillator in a spectrum analyzer. A variety of noise types (thermal, broadband operational amplifier, and popcorn noise) are evaluated, and measures to avoid the harmful constituents at each stage of the

R. Bales

1980-01-01

152

Relationship between Spatial Distribution of Noise Sources and Target Scatterings Observed in the 2010 Sea Trial of Ambient Noise Imaging  

NASA Astrophysics Data System (ADS)

An aspherical lens with an aperture diameter of 1.0 m has been designed and fabricated to develop a prototype system for ambient noise imaging (ANI). A sea trial of silent target detection using the prototype ANI system was conducted under only natural ocean ambient noise at Uchiura Bay, in November of 2010. It was verified that the targets are successfully detected under natural ocean ambient noise, mainly generated by snapping shrimps. In this study, we surveyed the relationship between the spatial distribution of noise sources and the target scattering captured by the ANI system. The observation using a pair of tetrahedron arrays was conducted at the same time as the sea trial. The estimated source positions were spread when the noises arrived from the sea bottom. Some of the sources were around the barge, and other sources were around fish preserves. On the other hand, the source positions were coincident with the barge when the noises arrived from the sea surface. The calculated scattering fields of the target showed sharp directivities. The locations of noise sources, where the ANI system can capture target scatterings with high intensities, were roughly determined at the barge around the sea surface.

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

2013-07-01

153

Stability and noise performance of constant transimpedance amplifier with inductive source  

Microsoft Academic Search

The design of a low-noise wideband transimpedance amplifier which matches an inductive source is considered. The presence of an inductive source makes it difficult to design such an amplifier to meet both low-noise and stability requirements. A novel feedback configuration is proposed. The use of this configuration gives good noise performance and at the same time realizes a constant transimpedance.

Z. Chang; W. M. C. Sansen

1989-01-01

154

Measurement and analysis of noise sources in giant magnetoresistive sensors up to 6 GHz  

Microsoft Academic Search

Describes the electrical and magnetic noise sources prevalent in giant magnetoresistive (GMR) sensors. At lower frequencies (<1 MHz), 1\\/f noise is generally dominant. Electrical (Nyquist-Johnson) and magnetic thermal fluctuation noise are dominant above 1 MHz. Because the GMR sensor resistance is current dependent (i.e., nonlinear), its electrical noise is higher than would be expected from its dc resistance. Noise measurements

Jason C. Jury; Klaas B. Klaassen; Jack C. L. van Peppen; Shan X. Wang

2002-01-01

155

Identification and Proposed Control of Helicopter Transmission Noise at the Source.  

National Technical Information Service (NTIS)

Helicopter cabin interiors require noise treatment which is expensive and adds weight. The gears inside the main power transmission are major sources of cabin noise. This paper describes work conducted by the NASA Lewis Research Center in measuring cabin ...

J. J. Coy R. F. Handschuh D. G. Lewicki R. G. Huff E. A. Krejsa

1987-01-01

156

A Probabilistic Algorithm Integrating Source Localization and Noise Suppression of MEG and EEG data  

Microsoft Academic Search

We have developed a novel probabilistic model that estimates neural source activity measured by MEG and EEG data while suppressing the effect of interference and noise sources. The model estimates contributions to sensor data from evoked sources, interference sources and sensor noise using Bayesian methods and by exploiting knowledge about their timing and spatial covariance properties. Full posterior distributions are

Johanna M. Zumer; Hagai Thomas Attias; Kensuke Sekihara; Srikantan S. Nagarajan

2006-01-01

157

A probabilistic algorithm integrating source localization and noise suppression for MEG and EEG data  

Microsoft Academic Search

We have developed a novel probabilistic model that estimates neural source activity measured by MEG and EEG data while suppressing the effect of interference and noise sources. The model estimates contributions to sensor data from evoked sources, interference sources and sensor noise using Bayesian methods and by exploiting knowledge about their timing and spatial covariance properties. Full posterior distributions are

Johanna M. Zumer; Hagai T. Attias; Kensuke Sekihara; Srikantan S. Nagarajan

2007-01-01

158

High harmonics from solid surfaces as a source of ultra-bright XUV radiation for experiments  

Microsoft Academic Search

The coherent high-order harmonic generation from the interaction of ultra- intense femtosecond laser pulses with solid density plasmas holds promise for tabletop sources of extreme ultraviolet (XUV) and soft x-ray radiation with attosecond duration and unprecedented intensities. Together with the generation of mono-energetic electron beams from gas jets and capillaries and the generation of mono-energetic ions from thin foils, this

159

Femtosecond dynamics and multiphoton ionization driven with an intense high order harmonic source  

Microsoft Academic Search

We have constructed a high intensity high order harmonic source delivering ~ 109 extreme ultraviolet photons\\/shot on a gas target and used it to observe multiphoton ionization and conduct femtosecond EUV-pump IR-probe experiments. Following excitation by 20-25 eV photons, we observed that the excited ethylene cation (H2C-CH2)+ experienced isomerization to the ethylidene configuration (HC-CHs)+ in 50±25 fs, followed by an

Jeroen van Tilborg; Tom Allison; Travis Wright; Marc Hertlein; Roger Falcone; Yanwei Liu; Hamed Merdji; Ali Belkacem

2009-01-01

160

Influence of the noise sources motion on the estimated Green's functions from ambient noise cross-correlations.  

PubMed

It has been demonstrated theoretically and experimentally that an estimate of the Green's function between two receivers can be obtained by cross-correlating acoustic (or elastic) ambient noise recorded at these two receivers. Coherent wavefronts emerge from the noise cross-correlation time function due to the accumulated contributions over time from noise sources whose propagation path pass through both receivers. Previous theoretical studies of the performance of this passive imaging technique have assumed that no relative motion between noise sources and receivers occurs. In this article, the influence of noise sources motion (e.g., aircraft or ship) on this passive imaging technique was investigated theoretically in free space, using a stationary phase approximation, for stationary receivers. The theoretical results were extended to more complex environments, in the high-frequency regime, using first-order expansions of the Green's function. Although sources motion typically degrades the performance of wideband coherent processing schemes, such as time-delay beamforming, it was found that the Green's function estimated from ambient noise cross-correlations are not expected to be significantly affected by the Doppler effect, even for supersonic sources. Numerical Monte-Carlo simulations were conducted to confirm these theoretical predictions for both cases of subsonic and supersonic moving sources. PMID:20550258

Sabra, Karim G

2010-06-01

161

Phase noise in signal sources /Theory and applications/  

NASA Astrophysics Data System (ADS)

A review of modulation theory is presented, taking into account amplitude modulation, phase modulation, frequency modulation, the addition of an arbitrary phase angle, linear approximation, phasor representation, the concept of conformability, and coherent demodulation of conformable signals. The relationship between phase jitter and noise density is considered along with noise induced frequency modulation, noise in oscillators, frequency multiplier chains, the use of phase lock loops, frequency synthesizers, the reciprocal relationships between phase noise and frequency stability (frequency domain to time domain transformations and their inverses, and system phase noise requirements. Subjects provided in an appendix include a summary of important formulae, a noise temperature and noise figure review, the quadrature representation of narrow band noise, the Q of varactor tuned oscillators, and the phase noise performance of Gunn oscillators.

Robins, W. P.

162

Reduction of electromagnetic force harmonics in asynchronous traction motor by adapting the rotor slot number  

Microsoft Academic Search

The harmonics in electromagnetic force are a source of mechanical vibration and audible noise in an asynchronous traction motor. This paper describes an approach to reduce the force harmonics by changing the rotor slot number. Both the radial and tangential forces acting on the stator teeth are calculated by Maxwell stress tensor and their time harmonics are examined by the

Byung-Taek Kim; Byun-Il Kwon; Seung-Chan Park

1999-01-01

163

Development of standalone coherent EUV scatterometry microscope with high-harmonic-generation EUV source  

NASA Astrophysics Data System (ADS)

For extreme ultraviolet (EUV) mask evaluation, we have developed the coherent EUV scatterometry microscope (CSM), which is equipped with a laboratory coherent EUV source for high-harmonic generation (HHG) and acts as a standalone EUV tool. The CSM records the diffraction from mask patterns directly with a charge-coupled-device (CCD) camera, which was illuminated with the coherent EUV light. The pattern image and the critical dimension values are evaluated by using the diffraction image with iterative calculations based on coherent diffraction imaging. The 59th high-order harmonic generation at a wavelength of 13.5 nm was pumped by a tabletop 6 mJ, 32 fs, Ti:sapphire laser system. EUV output energy of 1 ?W was successfully achieved. We observed the EUV mask using the HHG-CSM system. A very small 2 nm-wide line defect was successfully detected while located in an 88 nm line-and-space pattern.

Harada, Tetsuo; Nakasuji, Masato; Watanabe, Takeo; Nagata, Yutaka; Kinoshita, Hiroo

2012-06-01

164

HSCT Nozzle Source Noise Programs at Pratt and Whitney.  

National Technical Information Service (NTIS)

The topics covered include the following: 20 dB jet noise suppression; ejector nozzle technology program - noise reduction vs. flow augmentation; mixer ejector nozzle technology challenges; 1989 High Speed Civil Transport (HSCT) 2-D ejector model test in ...

A. M. Stern

1992-01-01

165

Determination of individual sound power levels of noise sources using a harmony search algorithm  

Microsoft Academic Search

Noise exposure is not only related to the non-auditory effects that endanger worker safety, but is also related to hearing loss. Permanent hearing loss and its associated problems are clearly a critical and widespread consequence of excessive noise exposure. Thus, it is necessary for industrial engineers to evaluate quantitatively the dominant noise source while multiple machines are running. This paper

Sungho Mun; Zong Woo Geem

2009-01-01

166

Source localization analysis using seismic noise data acquired in exploration geophysics  

NASA Astrophysics Data System (ADS)

Passive monitoring using seismic noise data shows a growing interest at exploration scale. Recent studies demonstrated source localization capability using seismic noise cross-correlation at observation scales ranging from hundreds of kilometers to meters. In the context of exploration geophysics, classical localization methods using travel-time picking fail when no evident first arrivals can be detected. Likewise, methods based on the intensity decrease as a function of distance to the source also fail when the noise intensity decay gets more complicated than the power-law expected from geometrical spreading. We propose here an automatic procedure developed in ocean acoustics that permits to iteratively locate the dominant and secondary noise sources. The Matched-Field Processing (MFP) technique is based on the spatial coherence of raw noise signals acquired on a dense array of receivers in order to produce high-resolution source localizations. Standard MFP algorithms permits to locate the dominant noise source by matching the seismic noise Cross-Spectral Density Matrix (CSDM) with the equivalent CSDM calculated from a model and a surrogate source position that scans each position of a 3D grid below the array of seismic sensors. However, at exploration scale, the background noise is mostly dominated by surface noise sources related to human activities (roads, industrial platforms,..), which localization is of no interest for the monitoring of the hydrocarbon reservoir. In other words, the dominant noise sources mask lower-amplitude noise sources associated to the extraction process (in the volume). Their location is therefore difficult through standard MFP technique. The Multi-Rate Adaptative Beamforming (MRABF) is a further improvement of the MFP technique that permits to locate low-amplitude secondary noise sources using a projector matrix calculated from the eigen-value decomposition of the CSDM matrix. The MRABF approach aims at cancelling the contributions of the dominant noise source by applying an orthogonal projection to the data matrix. It involves an iterative algorithm that will first detect and isolate the main noise source, and then localize a lower-amplitude source through the MFP procedure applied to the new projected dataset. Such processing was automatically applied to a seismic noise dataset acquired in a zone of shallow hydrocarbon extraction. The dataset consists of five-days continuous recordings by 397 geophones in a kilometer scale area. As expected, locations of dominant surface noise sources were in good agreement with human structures while secondary, weaker sources were located at depth and seem related to the extraction process in the hydrocarbon reservoir.

Roux, P.; Corciulo, M.; Campillo, M.; Dubuq, D.

2011-12-01

167

Generation and Radiation of Supersonic Jet Noise. Volume IV. Theory of Turbulence Generated Jet Noise, Noise Radiation from Upstream Sources, and Combustion Noise.  

National Technical Information Service (NTIS)

The report presents a series of specific theoretical studies directed toward the solution of jet noise generation and radiation, upstream noise radiation and combustion noise generation. Three theories are presented. Lilley's work is a new theory of jet n...

G. M. Lilley H. E. Plumblee P. E. Doak S. Y. Ruo W. C. Strahle

1972-01-01

168

Saturated and subcooled hydrothermal boiling in groundwater flow channels as a source of harmonic tremor  

NASA Astrophysics Data System (ADS)

The potential of hydrothermal boiling in groundwater flow channels for generating harmonic tremor (a relatively monochromatic ground vibration associated with volcanic activity) is examined. We use simple "organ pipe" theory of normal-mode fluid vibration and fundamental energy considerations to develop a first-order analytical model of a hydrothermal-boiling source of harmonic tremor. We use this model to estimate order-of-magnitude groundwater flow channel lengths and boiling heat transfer rates required to produce harmonic tremor with dominant frequencies in the range 0.5-5 Hz and surface wave reduced displacements of up to 100 cm2. Depending on groundwater sound speed, flow channel lengths of the order of 1-1000 m are required to produce fluid vibration eigenfrequencies in the range 0.5-5 Hz. The boiling heat transfer rate required to produce tremor with a given surface wave reduced displacement depends on the tremor frequency and on whether saturated boiling or subcooled boiling is the cause of the tremor. Saturated boiling produces groundwater vibration via steam bubble growth, whereas subcooled boiling produces groundwater vibration via steam bubble collapse. We find that subcooled hydrothermal boiling is from 102 to 104 times more efficient than saturated boiling in converting boiling "thermal" power to seismic power. For example, the boiling heat transfer rates required to produce 1-Hz tremor with reduced displacements of up to 100 cm2 via subcooled boiling are generally less than a few thousand megawatts; for saturated boiling, the required boiling heat transfer rates are several orders of magnitude larger than this. The highest values of heat flow reported in the literature for volcanic crater lakes and terrestrial and ocean floor geothermal areas are of the order of 1000 MW. Taking this value as a first-order estimate of an upper limit on possible boiling heat transfer rates in volcanic hydrothermal systems, our results suggest that saturated hydrothermal boiling is capable of generating only low-amplitude harmonic tremor, with surface wave reduced displacements no higher than a few square centimeters. However, subcooled hydrothermal boiling could potentially generate high-amplitude harmonic tremor, with reduced displacements as large as several hundred square centimeters. As a specific application of our model, we evaluate the potential of hydrothermal boiling for generating harmonic tremor at recently active Mount St. Helens and Nevado Del Ruiz volcanoes. We conclude that subcooled boiling likely could have produced the tremor episodes considered at both volcanoes. Saturated boiling also could explain the Nevado Del Ruiz tremor but probably not the more powerful Mount St. Helens tremor.

Leet, Robert C.

1988-05-01

169

Analysis and Control of Timing Jitter in Digital Logic Arising from Noise Voltage Sources  

Microsoft Academic Search

Timing jitter is an important factor in limiting throughput in high-performance digital circuits, e.g. those using techniques such as wave pipelining. Many of the sources of timing jitter, such as physical noise, coupling noise, and delta-I noise, are best modeled with random shifts in signal voltages. A new analysis technique for translating such noise into timing jitter characteristics is presented.

Perng-shyong Lin; Charles A. Zukowski

1993-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

171

Broadband second harmonic generation in GaAs nanowires by femtosecond laser sources  

NASA Astrophysics Data System (ADS)

Nonlinear optical property of semiconductor nanowires plays a key role in nanoscale optoelectronics. In this paper, we demonstrate an excellent frequency converter based on GaAs nanowires (NWs), in which second harmonic generation (SHG) is excited by femtosecond lasers from 800 nm to 1800 nm. Simultaneous SHG with a bandwidth of 300-nm is excited by a super-continuum source at 1000-1600 nm. Broadband SHG can also be acquired from an isolated single NW and the process is coherent. The experimental results suggest that GaAs NWs are potential broadband optical nonlinear converters in nanoscale optoelectronics.

He, Hao; Zhang, Xiaoqing; Yan, Xin; Huang, Lili; Gu, Chenglin; Hu, Ming-lie; Zhang, Xia; Ren, Xiao min; Wang, Chingyue

2013-09-01

172

Wavelength effect on atomic and molecular high harmonic generation driven by a tunable infrared parametric source.  

PubMed

We experimentally investigate the wavelength effect on high-order harmonic generation (HHG) in CH(4) molecules and Xe atoms driven by a tunable infrared parametric source, and observe that the molecular HHG around the vibrational resonance is more sensitive to the driver wavelength than HHG from an atomic gas with comparable ionization potential. The results can be attributed to the light nuclear motion induced by the driving laser field, and it becomes possible to control the proton vibration in the molecular HHG by tuning the infrared wavelength of the driving laser. PMID:19687984

Wei, Pengfei; Zhang, Chunmei; Liu, Candong; Huang, Yansui; Leng, Yuxin; Liu, Peng; Zheng, Yinghui; Zeng, Zhinan; Li, Ruxin; Xu, Zhizhan

2009-08-17

173

SCALE MODEL EXPERIMENTS ON NOISE REDUCTION SCALE MODEL EXPERIMENTS ON NOISE REDUCTION SCALE MODEL EXPERIMENTS ON NOISE REDUCTION SCALE MODEL EXPERIMENTS ON NOISE REDUCTION SCALE MODEL EXPERIMENTS ON NOISE REDUCTION BY ACOUSTIC BARRIER OF A STRAIGHT LINE SOURCE BY ACOUSTIC BARRIER OF A STRAIGHT LINE SOURCE BY ACOUSTIC BARRIER OF A STRAIGHT LINE SOURCE BY ACOUSTIC BARRIER OF A STRAIGHT LINE SOURCE BY ACOUSTIC BARRIER OF A STRAIGHT LINE SOURCE  

Microsoft Academic Search

SUMMARY Noise reduction by an acoustic barrier of a straight line source is examined with the aid of scale model experiments. The line source used in these experiments is an incoherent line source mechanically radiating broad band noise. From the experimental results a curve can be deduced which shows a relation between sound attenuation and Fresnel number N. This curve

Masaru KOYASU; Mitsuyasu YAMASHITA

1973-01-01

174

Movement variability resulting from different noise sources: a simulation study.  

PubMed

Limb movements are highly variable due in part to noise occurring at different stages of movement production, from sensing the position of the limb to the issuing of motor commands. Here we used a simulation approach to predict the effects of noise associated with (1) sensing the position of the limb ('position sensing noise') and (2) planning an appropriate movement vector ('trajectory planning noise'), as well as the combined effects of these factors, on arm movement variability across the workspace. Results were compared to those predicted by a previous model of the noise associated with movement execution. We found that the effects of sensing and planning related noise on movement variability were highly dependent upon both the planned movement direction and the initial configuration of the arm and differed in several respects from the effects of execution noise. In addition, sensing and planning noise interacted in a complex manner across movement directions. These results provide important insights into the relative roles of sensing, planning and execution noise in movement variability that could prove useful for understanding and addressing the exaggerated variability that arises from neurological damage, and for interpreting neurophysiological investigations that seek to relate neural variability to behavioral variability. PMID:22795761

Shi, Y; Buneo, C A

2012-07-13

175

Analysis of Error Sources in On-Wafer Noise Characterization of RF CMOS Transistors  

SciTech Connect

This paper analyzes how erroneous source impedance measurement due to residual errors within a VNA affect the four-noise parameter determination based on the cold-source noise measurement procedure and the eight-term linear model. It shows that although the errors disturb the complex noise characterization of a CMOS transistor at RF, mismatch and finite bandwidth errors seem to be more significant.

Wiatr, Wojciech [Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warsaw (Poland)

2005-08-25

176

/sup 252/Cf-source-driven neutron noise analysis method  

SciTech Connect

The /sup 252/Cf-source-driven neutron noise analysis method has been tested in a wide variety of experiments that have indicated the broad range of applicability of the method. The neutron multiplication factor k/sub eff/ has been satisfactorily detemined for a variety of materials including uranium metal, light water reactor fuel pins, fissile solutions, fuel plates in water, and interacting cylinders. For a uranyl nitrate solution tank which is typical of a fuel processing or reprocessing plant, the k/sub eff/ values were satisfactorily determined for values between 0.92 and 0.5 using a simple point kinetics interpretation of the experimental data. The short measurement times, in several cases as low as 1 min, have shown that the development of this method can lead to a practical subcriticality monitor for many in-plant applications. The further development of the method will require experiments oriented toward particular applications including dynamic experiments and the development of theoretical methods to predict the experimental observables.

Mihalczo, J.T.; King, W.T.; Blakeman, E.D.

1985-01-01

177

Noise from high speed maglev systems: Noise sources, noise criteria, preliminary design guidelines for noise control, recommendations for acoustical test facility for maglev research. Final report, July 1991-October 1992  

SciTech Connect

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.

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

1993-01-01

178

NUMERICAL PREDICTION OF AEROENGINE FAN STAGE TONE NOISE SOURCES USING CFD  

Microsoft Academic Search

This paper examines the extent to which 'conventional' low order accurate CFD codes can be applied to prediction of fan stage tone noise sources. Each of the major tone noise sources is consid ered in turn, with representative grid sizes estimated using assumptions about the capability of such codes. Simplifying approximations are also considered where they allow the more efficient

Alexander G. Wilson; John Coupland

179

On Short Period Ambient Noise of Taiwan (1) Ambient Noise Tomography (2) Probing Source of Ambient Noise  

NASA Astrophysics Data System (ADS)

Retrieving empirical Green functions (EGF) between stations by cross-correlating continuous seismic records has quickly become a popular technique in seismology for its operational simplicity and various advantages over traditional surface wave tomography; in particular, the derived short period Green’s functions of surface waves are usually inaccessible from seismic record caused by nature earthquakes. We apply this technique to three component continuous seismic data recorded at 88 short period stations in Taiwan. The data are collected from three seismic networks, including the island-wide Central Weather Bureau Seismic Network, and two temporary local seismic arrays, Tatun Volcanic Area array and Hsinchu array, for the time period from Jan, 2006 to Dec, 2006. For each station pairs, we derive Love waves from T-T (transverse) component cross-correlation functions (CCF), and Rayleigh waves from Z-Z (vertical) and R-R (radial) component CCF respectively. We measure group and phase velocities for the period range from 1 to 5 seconds. The achieved dense path coverage together with the retrieved short period EGF provide an unprecedented resolving power to the shallow crust structure of Taiwan island. With the qualified dispersion curves, we apply a multi-scale inversion technique to derive two dimensional phase, group velocity maps for both Rayleigh and Love waves, and three dimensional Vs structure of shallow crust. Besides tomographic study, we also attempt to probe the sources of ambient noise by several approaches: (1) analyzing the relative strength between the causal and acausal empirical Green’s functions (EGF); (2) measuring the relative strength of CCF amplitudes with respect to their own annual average as a function of time and azimuth to determine the background energy flow; and (3) computing power spectra density of continuous record for representative costal stations. With the results, we are able to characterize the spatial and temporal variations of CCF and their possible relationship to the atmospheric perturbations and coastal bathymetry.

Chen, Y.; Gung, Y.; You, S.; Chiao, L.; Liang, W.; Lin, C.

2009-12-01

180

Processing noise records with non-linear operations to select the distribution of noise sources contributing to the correlations  

NASA Astrophysics Data System (ADS)

: It is well known that in the 10-20s period band, cross-correlations of raw noise records usually do not provide the Green function of the medium. To overcome this two strategies exist : 1) applying a non-linear operations such as a 1bit normalization to the noise records prior to computing the correlations. 2) selecting carefully the time windows used to compute correlations to discard strong earthquakes, oceanic storms or instrumental glitch. These two strategies do not yield the same result. Using sourthern California data in the 10-20s period band, we show that correlations of 1bit and raw noise records (free from earthquake) are not sensitive to the same sources. Raw correlations see mostly local sources whereas 1bit correlations are sensitive to distant sources having strong seasonal variations. Moreover, the azimuthal distribution of noise sources contributing to 1bit correlations exhibits abrupt changes from day to day. This is a non-linear effect induced by the 1 bit normalization which is problematic for monitoring studies. Finally, we show it is possible to design a new non-linear operation with a free parameter allowing to move progressively from 1bit to raw correlation. It is then possible for instance 1) to use both local and distant sources when computing correlations (which is great for tomography), or 2) to diminish 1bit non-linear effects which is welcome for monitoring and attenuation studies.

Stehly, Laurent; Hanasoge, Sharvan

2013-04-01

181

Source localization from seismic noise: a methodology applied to seismic exploration.  

NASA Astrophysics Data System (ADS)

The main objective of the present study is to develop a methodology for source localization in seismic exploration contexts, using seismic noise data, which integrates methodologies optimized from acoustics and seismology. Passive imaging from noise cross-correlation is now applied at continental and regional scale. Its use at local scale for seismic exploration purposes is still uncertain. The development of passive imaging using cross-correlated data classically consists in two different tasks, the first one being the extraction of the Green's function from seismic noise and the second one consisting in modelling the velocity field from these observations. All the correlation methods are based on the concept that seismic noise is randomly distributed in space, in other words noise sources are azimuthally distributed around the recording stations. In practice, however, this never happens, especially at local scale and frequency above 1 Hz. A consequence is that the shape of the causal and anti-causal part of noise correlation function differs, which makes ambiguous the extraction of travel times for imaging purposes. Another consequence is that a third task should be added to the first two presented above that consists in the localization of the noise sources when it appears that the noise source distribution is heterogeneous. In our work we used data acquired in Northern America (Canada) on a 1-km side square seismic network. Five days of seismic noise data were collected on a total of 397 stations. Since exploration purposes need to obtain high resolution images and since noise correlation vanishes as frequency increases, we introduce a multistep procedure permitting to start our analysis from low to high frequency content. The seismic noise correlation function performed on the seismic network at low frequency [2-5 Hz] shows a large spatial coherence but also reveals a difference in amplitude for the causal and anti-causal parts of noise-correlated traces. Capitalizing on the strong coherence between station pairs, a methodology was developed, using both linear and non-linear techniques, to localize the seismic noise source(s). The linear technique is based on the minimization, as L2 norm, of the travel-times information extracted from the correlation functions and synthetic travel-times obtained from a local source at depth. Matched-Field Processing (MFP) non-linear techniques developed in ocean acoustics (and analogous to Capon's algorithm used in seismic) were used to further constraint the localization of the noise source on sub-wavelength dimensions. MFP results show that noise sources are quite stable on the 5 days of recording and source localization is well constrained in the low frequency range of interest.

Corciulo, Margherita; Roux, Philippe; Campillo, Michel; Dubucq, Dominique

2010-05-01

182

Analytic derivation of pinhole collimation sensitivity for a general source model using spherical harmonics  

PubMed Central

Pinhole collimators are widely used for SPECT imaging of small organs and animals. There also has been renewed interest in using pinhole arrays for clinical cardiac SPECT imaging to achieve high sensitivity and complete data sampling. Overall sensitivity of a pinhole array is critical in determining a system’s performance. Conventionally, a point source model has been used to evaluate the sensitivity and optimize the system design. This model is simple but far from realistic. This work addresses the use of more realistic source models to assess the sensitivity performance of pinhole collimation. We have derived an analytical formula for pinhole collimation sensitivity with a general source distribution model using spherical harmonics. As special cases of this general model, we provided the pinhole sensitivity formulae for line, disk and sphere sources. These results show that the point source model is just the zeroth-order approximation of the other source models. The point source model overestimates or underestimates the sensitivity relative to the more realistic model. The sphere source model yields the same sensitivity as a point source located at the center of the sphere when attenuation is not taken into account. In the presence of attenuation, the average path length of emitted gamma-rays is 3/4 of the radius of the sphere source. The calculated sensitivities based on these formulae show good agreement with separate Monte Carlo simulations in simple cases. The general and special sensitivity formulae derived here can be useful for the design and optimization of SPECT systems that utilize pinhole collimators.

Li, Yu-Sheng; Oldendick, James E; Chang, Wei

2013-01-01

183

Breaking wind waves as a source of ambient noise.  

PubMed

A theoretical model for the prediction of ambient noise level due to collective oscillations of air bubbles under breaking wind waves is presented. The model uses a budget of the energy flux from the breaking waves to quantify acoustic power radiation by a bubble cloud. A shift of the noise spectra to lower frequency due to collective bubble oscillation is assumed. The model derives good estimates of the magnitude, slope, and frequency range of the noise spectra using the wind speed or height of breaking waves. PMID:12186026

Tkalich, Pavlo; Chan, Eng Soon

2002-08-01

184

Control of tonal noise from subsonic axial fan. Part 1: reconstruction of aeroacoustic sources from far-field sound pressure  

NASA Astrophysics Data System (ADS)

An inverse method is investigated to evaluate the unsteady rotating forces (dipole strength distribution) acting by the fan on the fluid from far-field acoustic pressure measurements. A development based on the tonal noise generated by a propeller is used to derive a discretized form of the direct problem. The inversion of this direct problem is ill-posed and requires optimization technique to stabilize the solution for small perturbations in the measured acoustic input data. The reconstruction reveals that the conditioning of the inverse model depends on the aeroacoustic source and far-field sensor locations as well as on the frequency under investigation. Simulations show that an adequate choice of a regularization parameter leads to a satisfactory reconstruction of imposed unsteady rotating forces in the presence of measurement noise, and a correct localization of acoustic “hot spots” on the radiation surface. Preliminary experimental results also show the ability to extrapolate the radiated sound field at blade passage frequency (BPF), and harmonics, from the reconstructed forces. These data are exploited in the second part of this paper to evaluate various active control strategies for tonal fan noise.

Gérard, Anthony; Berry, Alain; Masson, Patrice

2005-12-01

185

Interaction between noise and lesion modeling errors on EEG source localization accuracy  

Microsoft Academic Search

EEG dipole source reconstruction requires the assumption of a source model and of a conductive head model. Head-modeling errors and measurement noise in the EEG induce localization errors in the results of EEG source analysis. In this study effects of brain lesions on EEG dipole source localization have been investigated by computer simulation. We present a sensitivity study quantifying the

P. Bruno; F. Vatta; P. Inchingolo

2001-01-01

186

A CMOS image sensor with reset level control using dynamic reset current source for noise suppression  

Microsoft Academic Search

A 512 × 384 CMOS image sensor in 0.18?m 1P4M technology with 5.9?m pixel pitch and a dynamic reset current source to compensate for kTC reset noise and fixed pattern noise is presented. A total of 390?V(rms) readout noise, and a factor of two improvement over conventional reset is achieved. The chip operates at 1.8V and consumes 40mW excluding I\\/O

Kwang-Hyun Lee; Euisik Yoon

2004-01-01

187

Aeroacoustics of modern transonic fans — Fan noise reduction from its sources  

Microsoft Academic Search

The noise of aerodynamics nature from modern transonic fan is examined from its sources with the perspective of noise reduction\\u000a through aero-acoustics design using advanced Computational Fluid Dynamics (CFD) tools. In particular the problems associated\\u000a with the forward propagating noise in the front is addressed. It is identified that the shock wave spillage from the leading\\u000a edge near the fan

L. Xu; J. D. Denton

2003-01-01

188

Aeroacoustics of Turbulent Jets: Flow Structure, Noise Sources, and Control  

NASA Astrophysics Data System (ADS)

The paper reviews research performed to advance the understanding of state-of-the-art technologies capable of reducing coaxial jet noise simulating the exhaust flow of turbofan engines. The review focuses on an emerging jet noise passive control technology known as chevron nozzles. The fundamental physical mechanisms responsible for the acoustic benefits provided by these nozzles are discussed. Additionally, the relationship between these physical mechanisms and some of the primary chevron geometric parameters are highlighted. Far-field acoustic measurements over a wide range of nozzle operating conditions illustrated the ability of the chevron nozzles to provide acoustic benefits. Detailed mappings of the acoustic near-field provided more insight into the chevron noise suppression mechanisms by successfully identifying two primary chevron effects consistent with the results of the far-field measurements: chevrons penetration and shear velocity across them. Mean and turbulence data identified the physical flow mechanisms responsible for the effects documented in the far- and near-field studies.

Gutmark, Ephraim Jeff; Callender, Bryan William; Martens, Steve

189

Long global gyrokinetic simulations: Source terms and particle noise control  

SciTech Connect

In global gyrokinetic simulations it takes a long time for the turbulence to reach a quasisteady state, and quantitative predictions about the quasisteady state turbulence have been difficult to obtain computationally. In particular, global particle-in-cell gyrokinetic simulations have been inefficient for long simulations due to the accumulation of noise. It is demonstrated that a simple Krook operator can effectively control noise; it also introduces an unphysical dissipation, which damps the zonal flows and can significantly affect simulation results even when the relaxation time is very long. However, it is possible to project out the effects of the Krook operator on the zonal flows. This permits noise accumulation to be controlled while preserving the physics of interest; simulations are then run to determine the level of quasisteady state transport and the variation across the ensemble of turbulent dynamics. Convergence is demonstrated both in the number of computational particles and the unphysical relaxation time.

McMillan, B. F.; Jolliet, S.; Tran, T. M.; Villard, L. [Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, PPB, 1015 Lausanne (Switzerland); Bottino, A. [Max Planck Institut fur Plasmaphysik, IPP-EURATOM Association, Garching (Germany); Angelino, P. [Association Euraton-CEA, CEA/DSM/DRFC Cadarache (France)

2008-05-15

190

New Technique for Calibrating Noise Sources at Millimetre and Submillimetre Wavelengths.  

National Technical Information Service (NTIS)

A new technique for calibrating noise sources in the far-infrared and millimetre wavelength range is described. Results obtained with a commercial neon gas discharge microwave noise tube in the range 60 < f < 900GHz and at a minimum resolution of 5 GHz ar...

A. E. Costley J. A. How D. R. Vizard

1978-01-01

191

Helicopter cabin noise: Methods of source and path identification and characterization  

Microsoft Academic Search

Internal noise sources in a helicopter are considered. These include propulsion machinery, comprising engine and transmission, and turbulent boundary layer effects. It is shown that by using relatively simple concepts together with careful experimental work it is possible to generate reliable data on which to base the design of high performance noise control treatments.

B. S. Murray; J. F. Wilby

1978-01-01

192

Noise Source Lumped Circuit Modeling and Identification for Power Converters  

Microsoft Academic Search

In this paper, a general lumped circuit modeling method is proposed to describe the conducted electromagnetic interference (EMI) coupling mechanism for the switching power converters. The EMI characteristics of the converters can be analytically deduced from a circuit theoretical viewpoint. The shunt and series impedance insertion method is introduced to identify the differential-mode (DM) and common-mode (CM) noise impedances and

Jin Meng; Weiming Ma; Qijun Pan; Zhihua Zhao; Lei Zhang

2006-01-01

193

Effects of noise levels and call types on the source levels of killer whale calls.  

PubMed

Accurate parameter estimates relevant to the vocal behavior of marine mammals are needed to assess potential effects of anthropogenic sound exposure including how masking noise reduces the active space of sounds used for communication. Information about how these animals modify their vocal behavior in response to noise exposure is also needed for such assessment. Prior studies have reported variations in the source levels of killer whale sounds, and a more recent study reported that killer whales compensate for vessel masking noise by increasing their call amplitude. The objectives of the current study were to investigate the source levels of a variety of call types in southern resident killer whales while also considering background noise level as a likely factor related to call source level variability. The source levels of 763 discrete calls along with corresponding background noise were measured over three summer field seasons in the waters surrounding the San Juan Islands, WA. Both noise level and call type were significant factors on call source levels (1-40 kHz band, range of 135.0-175.7 dB(rms) re 1 [micro sign]Pa at 1 m). These factors should be considered in models that predict how anthropogenic masking noise reduces vocal communication space in marine mammals. PMID:22087938

Holt, Marla M; Noren, Dawn P; Emmons, Candice K

2011-11-01

194

Walk-away VSP using drill noise as a source  

SciTech Connect

The authors describe a method for extracting and deconvolving a signal generated by a drill bit and collected by an array of surface geophones. The drill-noise signature is reduced to an effective impulse by means of a multichannel Wiener deconvolution technique, producing a walk-away reverse vertical seismic profile (VSP) sampled almost continuously in depth. They show how the multichannel technique accounts for noise and for internal drill-string reflections, automatically limiting the deconvolution technique, producing a walk-away reverse vertical seismic profile (VSP) sampled almost continuously in depth. They show how the multichannel technique accounts for noise and for internal drill-string reflections, automatically limiting the deconvolved data to frequencies containing significant energy. They have acquired and processed a data set from a well in Germany while drilling at a depth of almost 4,000 m. The subsurface image derived from these data compares well with corresponding images from a 3-d surface seismic survey, a zero-offset VSP survey, and a walk-away VSP survey acquired using conventional wireline techniques. The effective bandwidth of the deconvolved drill-noise data is comparable to the bandwidth of surface seismic data but significantly smaller than what can be achieved with wireline VSP techniques. Although the processing algorithm does not require the use of sensors mounted on the drill string, these sensors provide a very economic way to compress the data. The sensors on the drill string were also used for accurate timing of the deconvolved drill-noise data.

Haldorsen, J.B.U. [Geco-Prakla, Hannover (Germany); Miller, D.E. [Schlumberger-Doll Research, Ridgefield, CT (United States); Walsh, J.J. [Schlumberger Well Services, Houston, TX (United States)

1995-07-01

195

Identifying the principal noise sources of fixed-wing combat aircraft in high-speed flight  

Microsoft Academic Search

Before considering means for alleviating the noise from modern military combat aircraft operating in high-speed low-level flight, it is important to identify the principal noise sources. To this end, a carefully-controlled flight test program has been carried out using a Tornado aircraft (in standard training configuration) operating at flight speeds from 0.5M to 0.8M. The major sources of the aircraft

W. D. Bryce; R. A. Pinker; P. J. R. Strange

1992-01-01

196

Interaction Between Noise and Lesion Modeling Errors on EEG Source Localization Accuracy.  

National Technical Information Service (NTIS)

EEG dipole source reconstruction requires the assumption of a source model and of a conductive head model. Head-modeling errors and measurement noise in the EEG induce localization errors in the results of EEG source analysis. In this study effects of bra...

P. Bruno F. Vatta P. Inchingolo

2001-01-01

197

Can lightning be a noise source for a spherical gravitational wave antenna?  

NASA Astrophysics Data System (ADS)

The detection of gravitational waves is a very active research field at the moment. In Brazil the gravitational wave detector is called Mario SCHENBERG. Because of its high sensitivity it is necessary to model mathematically all known noise sources so that digital filters can be developed that maximize the signal-to-noise ratio. One of the noise sources that must be considered are the disturbances caused by electromagnetic pulses due to lightnings close to the experiment. Such disturbances may influence the vibrations of the antenna’s normal modes and mask possible gravitational wave signals. In this work we model the interaction between lightnings and SCHENBERG antenna and calculate the intensity of the noise due to a close lightning stroke in the detected signal. We find that the noise generated does not disturb the experiment significantly.

Magalhães, Nadja Simão; de Marinho, Rubens; de Aguiar, Odylio Denys; Frajuca, Carlos

2005-11-01

198

Recreational boating traffic: a chronic source of anthropogenic noise in the Wilmington, North Carolina Intracoastal Waterway.  

PubMed

The majority of attention on the impact of anthropogenic noise on marine mammals has focused on low-frequency episodic activities. Persistent sources of mid-frequency noise pollution are less well studied. To address this data gap, the contribution of 25 physical, biological and anthropogenic factors to the ambient noise levels in the Wilmington, North Carolina Intracoastal Waterway were analyzed using a principal components analysis and least squares regression. The total number of recreational vessels passing through the waterway per hour is the factor that had the single greatest influence on environmental noise levels. During times of high boat traffic, anthropogenic noise is continuous rather than episodic, and occurs at frequencies that are biologically relevant to bottlenose dolphins. As a daily part of resident bottlenose dolphins' acoustic environment, recreational boating traffic may represent a chronic source of acoustic harassment. PMID:17614475

Haviland-Howell, Genevieve; Frankel, Adam S; Powell, Christopher M; Bocconcelli, Alessandro; Herman, Russell L; Sayigh, Laela S

2007-07-01

199

Cortical Dipole Imaging for Multiple Signal Sources Considering Time-Varying Non-Uniform Noise  

NASA Astrophysics Data System (ADS)

Cortical dipole imaging is one of the spatial enhancement techniques from the scalp electroencephalogram. We investigated the dipole imaging for multiple signal sources under time-varying non-uniform noise conditions. The effects of incorporating statistical information of noise into the spatiotemporal inverse filter were examined by computer simulations and experimental studies in three sphere volume conductor model. The parametric projection filter that incorporated with noise covariance was applied to the inverse problem of EEG measurements. The noise covariance matrix was estimated by applying independent component analysis to the scalp potentials. The spatial filter was expanded to apply to the time-varying non-uniform noise conditions such as eye blink artifact. Moreover, multiple dipole distributions were introduced to extract and to visualize individual signal sources. The proposed imaging technique was applied to human experimental data of visual evoked potentials. We obtained reasonable results that coincide to physiological knowledge.

Hori, Junichi; Watanabe, Yoshiki

200

Fundamental and Harmonic Emission in Type III Solar Radio Bursts – III. Heliocentric Variation of Interplanetary Beam and Source Parameters  

Microsoft Academic Search

The parameters of type III solar radio sources have been observed to vary approximately as powers of the heliocentric distance. Recent theoretical studies of fundamental and harmonic emission are used to express the power-law exponents in terms of five basic ones. The results are then used to obtain a best fit to these five exponents, consistent with observed values of

P. A. Robinson; I. H. Cairns

1998-01-01

201

Emergence of deterministic Green's functions from noise generated by finite random sources.  

PubMed

Two-point correlation functions of sufficiently diffuse wave fields generated by uncorrelated random sources are known to approximate deterministic Green's functions between the two points. This property is utilized increasingly for passive imaging and remote sensing of the environment. Here we show that the relation between the Green's functions and the noise cross-correlation function holds under much less restrictive conditions than previously thought. It can even hold when ambient noise sources have correlation ranges large compared to the wavelength. Admissible correlation ranges are limited from above by the size of the Fresnel zone at wave propagation between the points where noise cross correlation is evaluated. PMID:20365292

Godin, Oleg A

2009-12-15

202

Comparison of noise properties of laser sources intended for multidimensional interferometric tools  

NASA Astrophysics Data System (ADS)

This work is oriented towards investigation of displacement measurement uncertainty contribution of different laser sources that are suitable for powering multidimensional interferometric positioning system for local probe microscopy. Main aim of this work was to find a suitable laser source for this measuring system. Most common 633 nm He-Ne lasers were compared with 532 nm frequency-doubled Nd:YAGs of different construction (external cavity doubling, ring configuration laser). We investigated amplitude and frequency noise of several lasers intended for micro- and nano- CMMs (coordinate measurement machines) and compared their noise properties together with the aim to find the best option. Amplitude noise measurements were done directly with the help of low noise photodetector, frequency noise of tested lasers was measured by two approaches - first with the help of Fabry-Perot resonator, which was used as a frequency discriminator converting a frequency (phase) noise into the amplitude one and second directly with the help of interferometer - measuring of interferometric fringe signal and position evaluation - another type of frequency discriminator. Both frequency noise and also amplitude noise measurements were done simultaneously to have a chance to compare both approaches and results.

Hrabina, Jan; Lazar, Josef; ?íp, Ondrej

2012-01-01

203

(Investigation of subcooled hydrothermal boiling in ground water flow channels as a source of harmonic tremors)  

SciTech Connect

As a first step toward assessing the ability of hydrothermal boiling to explain geothermal ground noise and volcanic tremor observations, we are investigating the acoustic power spectrum of boiling (the source'' spectrum in the above model). We simulate boiling in the lab by injecting high pressure steam from a boiler into a pressure vessel filled with water. The water pressure fluctuations that result from the repeated formation and collapse of steam bubbles at the steam inlet vents are recorded by a hydrophone whose output is digitized at 2 {times} 10{sup 4} samples/second by a computer. The range of pressure and temperature conditions attainable within the pressure vessel is limited to <3.5 bars, <139{degree}C, due to the finite strength of observation windows affixed to the pressure vessel. Therefore, dimensional analysis will be used to correlate the experimental results with the pertinent experimental variables. Besides the overall shape of the boiling power spectrum, we are investigating the absolute spectral levels in frequency bands typical of geothermal ground noise and volcanic tremor (0.5 Hz-10 Hz), and the ratio of acoustic power liberated to total available power. The values of these parameters are critical to hydrothermal boiling's ability to generate ground motion amplitudes in accordance with observation. If it can be shown that the range of observed ground noise/tremor amplitudes can be accounted for by hydrothermal boiling at reasonable heat transfer rates, this knowledge would be invaluable to designers of seismic monitoring experiments who are interested in geothermal resource exploration/evaluation and volcanic eruption prediction.

Not Available

1989-01-01

204

C2-4: Harmonizing Measures for Implementation Science Using Crowd-Sourcing  

PubMed Central

Background/Aims Implementation science (IS) is a priority topic in the renewal funding of the Cancer Research Network and encompasses a broad range of constructs and uses measures from a variety of disciplines. However, there has been little standardization of measures or agreement on definitions of constructs across different studies, fields, authors, or research groups. Moreover, many measures developed are not practical in real-world settings such as healthcare delivery systems. To further the field of IS, there is a need to both identify and evaluate IS measures on both their validity and practical relevance. Methods We describe a collaborative, web-based activity using the National Cancer Institute’s (NCI) Grid-Enabled Measures (GEM) portal that uses a wiki platform to focus discussion and engage the research community to enhance the quality and harmonization of measures for IS health-related research and practice. We present the history, process, and data from 8 months of the GEM Dissemination & Implementation (D&I) Campaign on IS measurement. Results The GEM D&I Campaign began in March 2012 and used a combination of expert opinion and crowd-sourcing approaches. To date, it has listed definitions for 45 constructs and summarized information for over 130 measures related to D&I. Measures identified and available include those in key domains such as organizational capacity, cost, reach/penetrance, stakeholder engagement, and adherence. Just under 60% of the D&I measures have at least one comment/rating. For 74 measures, the actual measure instrument is available for download. For those measure instruments available, they have been downloaded by users, on average, 93.8 times (range 2–1472). Conclusions To date, this campaign has provided information about different IS measures in many key domains, their associated characteristics, and comments. The next step is to increase the numbers and sources rating these measures for quality and practicality. Participation in this process by researchers and practitioners from practice-based settings such as the HMORN sites is crucial and could support the identification of practice-relevant measures for IS including ones measuring practice change capacity. We invite HMORN researchers to join this virtual community and help advance the quality and harmonization of IS measures and constructs.

Rabin, Borsika; Purcell, Peyton; Glasgow, Russell

2013-01-01

205

C2-4: harmonizing measures for implementation science using crowd-sourcing.  

PubMed

Background/Aims Implementation science (IS) is a priority topic in the renewal funding of the Cancer Research Network and encompasses a broad range of constructs and uses measures from a variety of disciplines. However, there has been little standardization of measures or agreement on definitions of constructs across different studies, fields, authors, or research groups. Moreover, many measures developed are not practical in real-world settings such as healthcare delivery systems. To further the field of IS, there is a need to both identify and evaluate IS measures on both their validity and practical relevance. Methods We describe a collaborative, web-based activity using the National Cancer Institute's (NCI) Grid-Enabled Measures (GEM) portal that uses a wiki platform to focus discussion and engage the research community to enhance the quality and harmonization of measures for IS health-related research and practice. We present the history, process, and data from 8 months of the GEM Dissemination & Implementation (D&I) Campaign on IS measurement. Results The GEM D&I Campaign began in March 2012 and used a combination of expert opinion and crowd-sourcing approaches. To date, it has listed definitions for 45 constructs and summarized information for over 130 measures related to D&I. Measures identified and available include those in key domains such as organizational capacity, cost, reach/penetrance, stakeholder engagement, and adherence. Just under 60% of the D&I measures have at least one comment/rating. For 74 measures, the actual measure instrument is available for download. For those measure instruments available, they have been downloaded by users, on average, 93.8 times (range 2-1472). Conclusions To date, this campaign has provided information about different IS measures in many key domains, their associated characteristics, and comments. The next step is to increase the numbers and sources rating these measures for quality and practicality. Participation in this process by researchers and practitioners from practice-based settings such as the HMORN sites is crucial and could support the identification of practice-relevant measures for IS including ones measuring practice change capacity. We invite HMORN researchers to join this virtual community and help advance the quality and harmonization of IS measures and constructs. PMID:24085970

Rabin, Borsika; Purcell, Peyton; Glasgow, Russell

2013-09-01

206

Numerical and experimental investigation of noise from small scale axial fans focusing on inflow condition and acoustic source type  

NASA Astrophysics Data System (ADS)

The objective of this work was to conduct an experimental and numerical investigation of the noise radiated by a small-scale axial fan from two different points-of-view: the development of an inflow treatment to compensate for unfavorable inflow conditions that result in excessive noise, and a consideration of installation effects for the acoustic source type of small axial fans. The effect of disturbed inflow on axial fans was experimentally investigated by intentionally placing a blockage plate at four different locations upstream of a fan. The blocked inflow made the axial fan perform very poorly; the severely decreased pressure performance introduced an overly strong dependence of flow performance on pressure load condition. An inflow diffuser made from aluminum foam was suggested to improve the aerodynamic and acoustic performance of the axial fan under such unfavorable inflow conditions. The inflow diffuser improved the stability of flow performance and reduced the blade passing tone by a small amount, but the levels of the high frequency harmonics of the blade passing tone were increased. A corresponding numerical model was built to model the flow change due to the inflow foam treatment. The inflow foam diffuser was approximated as a homogeneous porous zone to make the computational cost affordable, and it was shown that the model can predict the foam's influence on the pressure and flow performance of the fan. The aeroacoustic analogy model was applied to the solid surfaces of the fan and its housing to simulate the tonal noise at the blade passing frequency. The validity of the homogeneous foam model in terms of aeroacoustic predictions was also confirmed. As for the second aspect of the axial fan noise source, the dipole-like source behavior of an axial fan at the blade passing frequency was verified by directivity measurements. Thus, dipole modeling of an axial fan was justified. This result is associated with the problem of overestimated fan source strength due to the installation effect when measurements are made using an ISO 10302 plenum. A suggestion was made to compensate for this discrepancy. Further, by using the point dipole assumption as suggested, a method for mapping the sound radiation resistance when a fan is placed within a system enclosure was developed to help guide the positioning of axial fans within an enclosure so that they radiate the minimum sound power.

Shin, Yoon Shik

207

Detecting vocal fatigue in student singers using acoustic measures of mean fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio  

NASA Astrophysics Data System (ADS)

The purpose of this study is to explore the ability of four acoustic parameters, mean fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio, to detect vocal fatigue in student singers. The participants are 15 voice students, who perform two distinct tasks, data collection task and vocal fatiguing task. The data collection task includes the sustained vowel /a/, reading a standard passage, and self-rate on a vocal fatigue form. The vocal fatiguing task is the vocal practice of musical scores for a total of 45 minutes. The four acoustic parameters are extracted using the software EZVoicePlus. The data analyses are performed to answer eight research questions. The first four questions relate to correlations of the self-rating scale and each of the four parameters. The next four research questions relate to differences in the parameters over time using one-factor repeated measures analysis of variance (ANOVA). The result yields a proposed acoustic profile of vocal fatigue in student singers. This profile is characterized by increased fundamental frequency; slightly decreased jitter; slightly decreased shimmer; and slightly increased harmonics-to-noise ratio. The proposed profile requires further investigation.

Sisakun, Siphan

208

Multi-MW 22.8 GHz Harmonic Multiplier - RF Power Source for High-Gradient Accelerator R&D  

SciTech Connect

Electrodynamic and particle simulation studies have been carried out to optimize design of a two-cavity harmonic frequency multiplier, in which a linear electron beam is energized by rotating fields near cyclotron resonance in a TE111 cavity in a uniform magnetic field, and in which the beam then radiates coherently at the nth harmonic into a TEn11 output cavity. Examples are worked out in detail for 7th and 2nd harmonic converters, showing RF-to-RF conversion efficiencies of 45% and 88%, respectively at 19.992 GHz (K-band) and 5.712 GHz (C-band), for a drive frequency of 2.856 GHz. Details are shown of RF infrastructure (S-band klystron, modulator) and harmonic converter components (drive cavity, output cavities, electron beam source and modulator, beam collector) for the two harmonic converters to be tested. Details are also given for the two-frequency (S- and C-band) coherent multi-MW test stand for RF breakdown and RF gun studies.

Jay L. Hirshfield

2012-07-26

209

Estimated generalized least squares electromagnetic source analysis based on a parametric noise covariance model [EEG\\/MEG  

Microsoft Academic Search

Estimated generalized least squares (EGLS) electromagnetic source analysis is used to downweight noisy and correlated data. Standard EGLS requires many trials to accurately estimate the noise covariances and, thus, the source parameters. Alternatively, the noise covariances can be modeled parametrically. Only the parameters of the model describing the noise covariances need to be estimated and, therefore, less trials are required.

P. C. M. Molenaar; C. V. Dolan; H. M. Huizenga; L. J. Waldorp

2001-01-01

210

Methods for Designing Treatments to Reduce Interior Noise of Predominant Sources and Paths in a Single Engine Light Aircraft.  

National Technical Information Service (NTIS)

The sources and paths by which noise enters the cabin of a small single engine aircraft were determined through a combination of flight and laboratory tests. The primary sources of noise were found to be airborne noise from the propeller and engine casing...

R. E. Hayden P. J. Remington M. A. Theobald J. F. Wilby

1985-01-01

211

Coastal wave reflection, directional spread, and seismoacoustic noise sources  

NASA Astrophysics Data System (ADS)

Coastal reflection is introduced in a phase-averaged numerical wave model, first with a constant coefficient, and then with a reflection coefficient defined from the shoreface slope and that depends on the incident wave height and mean frequency. This parameterization is used in both regular and unstructured grids. The calibration involves a site-specific shoreface slope that is associated with the local geomorphology of the shoreline. Using wave buoy data off Hawaii and the U.S. West Coast, it is found that coastal reflection is necessary to reproduce observed directional properties of coastal sea states. Errors on the mean directional spread are reduced by up to 30% for the frequency band 0.04 to 0.30 Hz with, at most locations, very little impact on the mean direction and energy levels. The most accurate results are obtained using the parameterization based on the shoreface slope, provided that this slope is estimated accurately. These parameterizations are validated using seismic noise data. Using data from the U.S. West Coast it is shown that the reflection defined from the shoreface slope can improve the correlation between measured and modeled seismic noise.

Ardhuin, Fabrice; Roland, Aron

2012-11-01

212

Experimental study of dynamic and noise produced by a gearing excited by a multi-harmonic excitation  

Microsoft Academic Search

This paper deals with the rattle noise, caused by the fluctuation of the engine torque (acyclic excitation) which, under special conditions, can cause multiple impacts inside the gearbox. Its aim is to experimentally describe the rattle phenomenon in a gearbox. First, a fully instrumented test rig consisting of a simplified gearbox was designed in order to recreate the rattle noise

M. Barthod; B. Hayne; J.-L. Tébec; J.-C. Pin

2007-01-01

213

Exposures to transit and other sources of noise among New York City residents.  

PubMed

To evaluate the contributions of common noise sources to total annual noise exposures among urban residents and workers, we estimated exposures associated with five common sources (use of mass transit, occupational and nonoccupational activities, MP3 player and stereo use, and time at home and doing other miscellaneous activities) among a sample of over 4500 individuals in New York City (NYC). We then evaluated the contributions of each source to total noise exposure and also compared our estimated exposures to the recommended 70 dBA annual exposure limit. We found that one in ten transit users had noise exposures in excess of the recommended exposure limit from their transit use alone. When we estimated total annual exposures, 90% of NYC transit users and 87% of nonusers exceeded the recommended limit. MP3 player and stereo use, which represented a small fraction of the total annual hours for each subject on average, was the primary source of exposure among the majority of urban dwellers we evaluated. Our results suggest that the vast majority of urban mass transit riders may be at risk of permanent, irreversible noise-induced hearing loss and that, for many individuals, this risk is driven primarily by exposures other than occupational noise. PMID:22088203

Neitzel, Richard L; Gershon, Robyn R M; McAlexander, Tara P; Magda, Lori A; Pearson, Julie M

2011-12-08

214

A low phase noise microwave source for atomic spin squeezing experiments in {sup 87}Rb  

SciTech Connect

We describe and characterize a simple, low cost, low phase noise microwave source that operates near 6.800 GHz for agile, coherent manipulation of ensembles of {sup 87}Rb. Low phase noise is achieved by directly multiplying a low phase noise 100 MHz crystal to 6.8 GHz using a nonlinear transmission line and filtering the output with custom band-pass filters. The fixed frequency signal is single sideband modulated with a direct digital synthesis frequency source to provide the desired phase, amplitude, and frequency control. Before modulation, the source has a single sideband phase noise near -140 dBc/Hz in the range of 10 kHz-1 MHz offset from the carrier frequency and -130 dBc/Hz after modulation. The resulting source is estimated to contribute added spin-noise variance 16 dB below the quantum projection noise level during quantum nondemolition measurements of the clock transition in an ensemble 7 x 10{sup 5} {sup 87}Rb atoms.

Chen Zilong; Bohnet, Justin G.; Weiner, Joshua M.; Thompson, James K. [JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440 (United States)

2012-04-15

215

A low phase noise microwave source for atomic spin squeezing experiments in 87Rb.  

PubMed

We describe and characterize a simple, low cost, low phase noise microwave source that operates near 6.800 GHz for agile, coherent manipulation of ensembles of (87)Rb. Low phase noise is achieved by directly multiplying a low phase noise 100 MHz crystal to 6.8 GHz using a nonlinear transmission line and filtering the output with custom band-pass filters. The fixed frequency signal is single sideband modulated with a direct digital synthesis frequency source to provide the desired phase, amplitude, and frequency control. Before modulation, the source has a single sideband phase noise near -140 dBc/Hz in the range of 10 kHz-1 MHz offset from the carrier frequency and -130 dBc/Hz after modulation. The resulting source is estimated to contribute added spin-noise variance 16 dB below the quantum projection noise level during quantum nondemolition measurements of the clock transition in an ensemble 7 × 10(5) (87)Rb atoms. PMID:22559559

Chen, Zilong; Bohnet, Justin G; Weiner, Joshua M; Thompson, James K

2012-04-01

216

Clutter isolation and cardiac monitoring using harmonic doppler radar with heterodyne receiver and passive RF tags.  

PubMed

A harmonic radar employing the use of harmonic passive RF tags can be successfully used to isolate the human respiration from environmental clutter. This paper describes the successful use of heterodyne receiver architecture with Doppler radar to track the heart-rate of a human being using passive body-worn harmonic tags in presence of a controlled noise generator at distances up to 120 cm. The heterodyne system results have been compared with those of a conventional Doppler radar for cardiopulmonary monitoring that fails to isolate the noise from heart-rate in presence of a noise source. PMID:21096353

Singh, Aditya; Lubecke, Victor

2010-01-01

217

Preliminary investigation on apparent seismic velocity variations caused by microseism noise source variability  

NASA Astrophysics Data System (ADS)

Currently there is strong interest in monitoring temporal changes in seismic wave velocity in various geological settings. These settings can range from volcano monitoring to reservoir monitoring amongst others. Green's functions are often used to monitor temporal variations in seismic velocity as their arrival times contain information about velocity changes. The velocities can be measured through the cross correlation of Green's functions for a given pair of stations. Correlation of ambient noise is typically used for Green's function retrieval. The great advantage of using noise is that noise is continuous in time and there are no natural explosive or repeatable sources required. However temporal and spatial variations of non-uniformly distributed noise sources may lead to apparent changes in Green's functions which are related to the source not the path. This could lead to a misinterpretation of temporal changes in wave velocity. Ireland is a good location in which to study these effects, as it is tectonically very quiet and is relatively close to large noise sources in the North Atlantic. The spatial and temporal distribution of noise sources are being tracked using seismic arrays deployed in Ireland under a sister project (called WaveObs). Concurrently, in this project, we are searching for temporal variations in wave velocity using noise correlation and comparing them to the temporal and spatial distribution of the noise sources as determined under the WaveObs project. The aims of this project are to find out how the waveform and the arrival time of the Green's functions correlate with spatial and temporal variability of the noise sources and what minimum trace length of noise is required for the Green's functions to converge. The expected outcome of the project is therefore an assessment of the degree to which velocity variations are caused by changes in the sources. Hence, these lemiting conditions can be considered when this method is used in a different setting where we expect velocities to change rapidly e.g. on a volcano or in a reservoir.

Friderike Volk, Meike; Bean, Christopher; Lokmer, Ivan

2013-04-01

218

Fan Noise Source Diagnostic Test: Rotor Alone Aerodynamic Performance Results.  

National Technical Information Service (NTIS)

The aerodynamic performance of an isolated fan or rotor alone model was measured in the NASA Glenn Research Center 9- by 15- Foot Low Speed Wind Tunnel as part of the Fan Broadband Source Diagnostic Test conducted at NASA Glenn. The Source Diagnostic Test...

C. E. Hughes R. J. Jeracki R. P. Woodward C. J. Miller

2005-01-01

219

Sound source localization of filtered noises by listeners with normal hearing: a statistical analysis.  

PubMed

Several measures of sound source localization performance of 45 listeners with normal hearing were obtained when loudspeakers were in the front hemifield. Localization performance was not statistically affected by filtering the 200-ms, 2-octave or wider noise bursts (125 to 500, 1500 to 6000, and 125 to 6000?Hz wide noise bursts). This implies that sound source localization performance for noise stimuli is not differentially affected by which interaural cue (interaural time or level difference) a listener with normal hearing uses for sound source localization, at least for relatively broadband signals. This sound source localization task suggests that listeners with normal hearing perform with high reliability/repeatability, little response bias, and with performance measures that are normally distributed with a mean root-mean-square error of 6.2° and a standard deviation of 1.79°. PMID:23654393

Yost, William A; Loiselle, Louise; Dorman, Michael; Burns, Jason; Brown, Christopher A

2013-05-01

220

Harmonic Allocation of Authorship Credit: Source-Level Correction of Bibliometric Bias Assures Accurate Publication and Citation Analysis  

PubMed Central

Authorship credit for multi-authored scientific publications is routinely allocated either by issuing full publication credit repeatedly to all coauthors, or by dividing one credit equally among all coauthors. The ensuing inflationary and equalizing biases distort derived bibliometric measures of merit by systematically benefiting secondary authors at the expense of primary authors. Here I show how harmonic counting, which allocates credit according to authorship rank and the number of coauthors, provides simultaneous source-level correction for both biases as well as accommodating further decoding of byline information. I also demonstrate large and erratic effects of counting bias on the original h-index, and show how the harmonic version of the h-index provides unbiased bibliometric ranking of scientific merit while retaining the original's essential simplicity, transparency and intended fairness. Harmonic decoding of byline information resolves the conundrum of authorship credit allocation by providing a simple recipe for source-level correction of inflationary and equalizing bias. Harmonic counting could also offer unrivalled accuracy in automated assessments of scientific productivity, impact and achievement.

Hagen, Nils T.

2008-01-01

221

Harmonic allocation of authorship credit: source-level correction of bibliometric bias assures accurate publication and citation analysis.  

PubMed

Authorship credit for multi-authored scientific publications is routinely allocated either by issuing full publication credit repeatedly to all coauthors, or by dividing one credit equally among all coauthors. The ensuing inflationary and equalizing biases distort derived bibliometric measures of merit by systematically benefiting secondary authors at the expense of primary authors. Here I show how harmonic counting, which allocates credit according to authorship rank and the number of coauthors, provides simultaneous source-level correction for both biases as well as accommodating further decoding of byline information. I also demonstrate large and erratic effects of counting bias on the original h-index, and show how the harmonic version of the h-index provides unbiased bibliometric ranking of scientific merit while retaining the original's essential simplicity, transparency and intended fairness. Harmonic decoding of byline information resolves the conundrum of authorship credit allocation by providing a simple recipe for source-level correction of inflationary and equalizing bias. Harmonic counting could also offer unrivalled accuracy in automated assessments of scientific productivity, impact and achievement. PMID:19107201

Hagen, Nils T

2008-12-24

222

Signal-to-noise ratio of intensity interferometry experiments with highly asymmetric x-ray sources  

SciTech Connect

The authors discuss the signal-to-noise ratio of an intensity interferometry experiment for a highly asymmetric x-ray source using different aperture shapes in front of the photodetectors. It is argued that, under ideal conditions using noiseless detectors and electronics, the use of slit-shaped apertures, whose widths are smaller but whose lengths are much greater than the transverse coherence widths of the beam in the corresponding directions, provides no signal-to-noise advantage over the use of pinhole apertures equal to or smaller than the coherence area. As with pinholes, the signal-to-noise ratio is determined solely by the count degeneracy parameter and the degree of coherence of the beam. This contrasts with the signal-to-noise ratio enhancement achievable using slit-shaped apertures with an asymmetric source in a Young`s experiment.

Feng, Y.P.; McNulty, I.; Xu, Z.; Gluskin, E. [Argonne National Lab., IL (United States). Experimental Facilities Div.

1995-06-23

223

Signal-to-noise ratio of intensity interferometry experiments with highly asymmetric x-ray sources  

SciTech Connect

We discuss the signal-to-noise ratio of an intensity interferometry experiment for a highly asymmetric x-ray source using different aperture shapes in front of the photodetectors. It is argued that, under ideal conditions using noiseless detectors and electronics, the use of slit-shaped apertures, whose widths are smaller but whose lengths are much greater than the transverse coherence widths of the beam in the corresponding directions, provides no signal-to-noise advantage over the use of pinhole apertures equal to or smaller than the coherence area. As with pinholes, the signal-to-noise ratio is determined solely by the count degeneracy parameter and the degree of coherence of the beam. This contrasts with the signal-to-noise ratio enhancement achievable using slit-shaped apertures with an asymmetric source in a Young`s experiment.

Feng, Y.P.; McNulty, I.; Xu, Z.; Gluskin, E.

1997-02-11

224

New correlation model for the cascade of turbulent pulsations as a noise source in jets  

NASA Astrophysics Data System (ADS)

The mechanisms of noise generation by turbulent jets associated with a cascade of turbulent perturbations are considered from generation of primary eddies to their disintegration. A new correlation model proposed for describing these mechanisms is based on simulation of their generation as a random process with deterministic description of individual eddies. The model makes it possible to analyze available correlation models based on experimental modeling of the correlation function: monopoles, dipoles, or quadrupoles. The main difference between these models is both the different multipole structure of assumed sources and implicit "hard" and "soft" variants of source generation, as well as in the main variable for which the correlation function is developed. This approach is used for developing the correlation model of the noise generation mechanism related to oscillations of surface eddies. The jet noise inferred from the proposed model is well consistent with experimental data on circular jet noise.

Kopiev, V. F.; Chernyshev, S. A.

2012-07-01

225

Additive Gaussian white noise modulated excitation kinetics of impurity doped quantum dots: Role of confinement sources  

NASA Astrophysics Data System (ADS)

We investigate the excitation kinetics of a repulsive impurity doped quantum dot initiated by the application of additive Gaussian white noise. The noise and the dot confinement sources of electric and magnetic origin have been found to fabricate the said kinetics in a delicate way. In addition to this the dopant location also plays some prominent role. The present study sheds light on how the individual or combined variation of different confinement sources could design the excitation kinetics in presence of noise. The investigation reveals emergence of maximization and saturation in the excitation kinetics as a result of complex interplay between various parameters that affect the kinetics. The phase space plots are often invoked and they lend credence to the findings. The present investigation is believed to provide some useful perceptions of the functioning of mesoscopic systems where noise plays some profound role.

Ganguly, Jayanta; Pal, Suvajit; Ghosh, Manas

2013-11-01

226

Stochastic transport theory analysis of the Cf252 Source Driven Noise Technique  

Microsoft Academic Search

This report presents a derivation of the relationship between the reactivity of a subcritical nuclear system and the quantity measured by the Cf-252 Source Driven Noise Technique. This experimental method uses the output signals of a fission chamber containing a Cf-252 source and those of two neutron detectors to form a particular ratio of four auto- and cross-power spectral densities.

T. M. Sutton; W. B. Doub

1991-01-01

227

Estimating Free Field, Far Field Radiated Noise Source Levels from Measurements Acquired in a Harbor Environment.  

National Technical Information Service (NTIS)

The radiated noise of ships or other underwater sources are typically characterized in terms of a far-field, plane-wave equivalent source level based on measurements assumed to have been acquired m a free field environment such as a deep water test range....

B. Fowler D. C. Barber

2012-01-01

228

An ensemble source spectra model for merchant ship-radiated noise  

Microsoft Academic Search

This paper presents an evaluation of the classical model for determining an ensemble of the broadband source spectra of the sound generated by individual ships and proposes an alternate model to overcome the deficiencies in the classical model. The classical model, proposed by Ross [Mechanics of Underwater Noise (Pergamon, New York, 1976)] postulates that the source spectrum for an individual

Stephen C. Wales; Richard M. Heitmeyer

2002-01-01

229

Low frequency noise sources in InAlAs\\/InGaAs MODFETs  

Microsoft Academic Search

Detailed analysis of the 1\\/f low-frequency noise (LFN) in In0.52Al0.48As\\/InGaAs MODFET structures is performed, for low drain bias (below pinch-off voltage), in order to identify the physical origin and the location of the noise sources responsible for drain current fluctuations in the frequency range 0.1 Hz-105 Hz. Experimental data were analyzed with the support of a general modeling of the

P. Viktorovitch; P. Rojo-Romeo; J. L. Leclercq; X. Letartre; Jacques Tardy; M. Oustric; M. Gendry

1996-01-01

230

A Low Phase Noise Quadrature LC VCO Using Capacitive Common-Source Coupling  

Microsoft Academic Search

A low phase noise quadrature LC VCO with inherent tail-current shaping is presented. Two identical differential LC VCOs are locked in quadrature with a capacitor connected between their common-source nodes. This capacitor further drives the oscillators into a tail-current shaping mode, which increases their oscillation amplitude and reduces their phase noise. A multi-band 1.9 GHz differential nMOS quadrature LC VCO

B. Soltanian; P. Kinget

2006-01-01

231

Detection of a weak target in the presence of loud moving noise sources  

Microsoft Academic Search

A previous study [J. Acoust. Soc. Am. 112 (2002)] treated the detection of a weak target in an adverse shallow-water environment with ambient noise and ``known'' interfering ships by applying a model-based adaptive (recursive) technique. The shallow-water environment and noise sources were represented by a normal-mode model directly incorporated into the model-based processor, thereby allowing their effects to be removed

Edmund J. Sullivan; James V. Candy; William M. Carey

2003-01-01

232

Detection of microseismic compressional (P) body waves aided by numerical modeling of oceanic noise sources  

NASA Astrophysics Data System (ADS)

Among the different types of waves embedded in seismic noise, body waves present appealing properties but are still challenging to extract. Here we first validate recent improvements in numerical modeling of microseismic compressional (P) body waves and then show how this tool allows fast detection and location of their sources. We compute sources at ~0.2 Hz within typical P teleseismic distances (30-90°) from the Southern California Seismic Network and analyze the most significant discrete sources. The locations and relative strengths of the computed sources are validated by the good agreement with beam-forming analysis. These 54 noise sources exhibit a highly heterogeneous distribution, and cluster along the usual storm tracks in the Pacific and Atlantic oceans. They are mostly induced in the open ocean, at or near water depths of 2800 and 5600 km, most likely within storms or where ocean waves propagating as swell meet another swell or wind sea. We then emphasize two particularly strong storms to describe how they generate noise sources in their wake. We also use these two specific noise bursts to illustrate the differences between microseismic body and surface waves in terms of source distribution and resulting recordable ground motion. The different patterns between body and surface waves result from distinctive amplification of ocean wave-induced pressure perturbation and different seismic attenuation. Our study demonstrates the potential of numerical modeling to provide fast and accurate constraints on where and when to expect microseismic body waves, with implications for seismic imaging and climate studies.

Obrebski, Mathias; Ardhuin, Fabrice; Stutzmann, Eleonore; Schimmel, Martin

2013-08-01

233

An improved assessment approach for noise impacts from stationary point and traffic sources on humans and wildlife  

SciTech Connect

This paper presents an improved, efficient approach for assessing noise impacts associated with a complex set of noise sources at multiple receptor locations; noise impacts form typical remedial activities at a contaminated industrial site are used as an example. The noise sources associated with remedial activities at the site and surrounding areas are described, the noise-propagation modeling methods and results are presented, and an impact assessment of the contaminated site is discussed with regard to applicable regulatory standards and individual and community responses. Also discussed is the improved noise assessment approach. The improved features demonstrated are automate approaches for (1) inputting long-term hourly meterorological data (e.g., 8,760 hours for a one-year period) into a long-range noise-propagation model for computing noise-level increases at receptor locations and (2) analyzing potential individual and community responses to intrusive noises using the IAP and modified CNR.

Chang, Young-Soo; Chun, K.C.

1994-04-01

234

High-Speed Jet Noise Source Identification by Wavelet Filtering  

NASA Astrophysics Data System (ADS)

Pressure sensors in a Mach 0.6 jet provide near-field data at 2 sections (x/D = 3 and 6), and simultaneous far-field data at 5 angular locations from 15^o to 90^oo degrees relative to the jet axis. Continuous wavelets allow some feature recognition at the various stations. In the absence of sustained oscillations, the Mexican hat wavelet is used on the Fourier mode 0 in the near-field. At each scale, some local extrema (presumed signature of a nearby vortex) are recognized, with delay, between the 2 stations, and a scale-dependent convection speed is calculated. Non-linear filtering isolates the recognized, "matched" features, at the 2 near-field stations, and a `residue' presumed to include the result of vortex pairing or breakdown. The physical relevance of this decomposition is established by the cross-correlation of the filtered near-field data with far-field noise. A scale-dependent cross-correlation was calculated, showing distinct scales and convection propagation delays for the various pairs of traces, for which different causes will be discussed. At the time of writing, the distinctive characteristics are used for pattern recognition in the raw data.

Lewalle, Jacques; Berger, Zachary; Low, Kerwin; Glauser, Mark

2010-11-01

235

Saturated and subcooled hydrothermal boiling in groundwater flow channels as a source of harmonic tremor  

Microsoft Academic Search

The potential of hydrothermal boiling in groundwater flow channels for generating harmonic tremor (a relatively monochromatic ground vibration associated with volcanic activity) is examined. We use simple ``organ pipe'' theory of normal-mode fluid vibration and fundamental energy considerations to develop a first-order analytical model of a hydrothermal-boiling souce of harmonic tremor. We use this model to estimate order-of-magnitude groundwater flow

Robert C. Leet

1988-01-01

236

Prediction of wake-interaction noise in axial-flow machines - Application to helicopter fenestron  

NASA Astrophysics Data System (ADS)

A wake model based on experimental measurements is used to determine the noise generated by rotor-stator interactions in an axial-flow machine. Application of the model to the tail rotor of a helicopter shows that the 3rd to 9th harmonics of the blade passing frequency can be attributed to this noise source. Neither the first two harmonics nor the large-band noise are attributed to wake interactions.

Fournier, Francette; Roger, Michel

1989-03-01

237

MEASUREMENT OF KINETIC PARAMETERS IN THE SOURCE DRIVEN FAST SUBCRITICAL CORE MASURCA WITH NOISE METHODS  

Microsoft Academic Search

In the framework of the European 5FP MUSE measurements are performed to investigate the neutronic behaviour of the fast subcritical core MASURCA coupled with the pulsed GENEPI neutron generator. Noise techniques, such as the Rossi-alpha method, Feynman-alpha and spectral methods were applied in several measurement conditions. Different driving sources were used: the intrinsic plutonium source and a pulsed neutron source.

P. BAETEN; G. IMEL; C. DESTOUCHES; C. JAMMES; F. MELLIER; G. PERRET; E. GONZALEZ-ROMERO; D. VILLAMARIN

238

Radiation of Spatially Incoherent Noise: Circular and Rectangular Plane Sources.  

National Technical Information Service (NTIS)

The concept of spatially incoherent (SI) radiation has been applied to extended sources. The fields of SI-radiating circular disks and rectangles have been calculated for uniform radiation and for a square law decrease (of power radiated per unit area) to...

V. Salmon K. N. Sawyers

1968-01-01

239

A study of active power filters using quad-series voltage-source PWM converters for harmonic compensation  

Microsoft Academic Search

An active power filter using quad-series voltage-source pulse-width-modulated (PWM) converters to suppress AC harmonics by injecting compensating currents into the AC system is described. The circuit used to calculate the compensating current references, the compensation characteristics, and the capability of the DC capacitor are discussed theoretically and experimentally. A control circuit for the DC capacitor voltage is proposed. The discussions

FANG-ZHANG PENG; HIROFUMI AKAGI; AKIRA NABAE

1990-01-01

240

Source directionality of ambient seismic noise inferred from three-component beamforming  

NASA Astrophysics Data System (ADS)

AbstractThe increased use of ambient seismic <span class="hlt">noise</span> for seismic imaging requires better understanding of the ambient seismic <span class="hlt">noise</span> wavefield and its <span class="hlt">source</span> locations and mechanisms. Although the <span class="hlt">source</span> regions and mechanisms of Rayleigh waves have been studied extensively, characterization of Love wave <span class="hlt">source</span> processes are sparse or absent. We present here the first systematic comparison of ambient seismic <span class="hlt">noise</span> <span class="hlt">source</span> directions within the primary (~10-20 s period) and secondary (~5-10 s period) microseism bands for both Rayleigh and Love waves in the Southern Hemisphere using vertical- and horizontal-component ambient seismic <span class="hlt">noise</span> recordings from a dense temporary network of 68 broadband seismometers in New Zealand. Our analysis indicates that Rayleigh and Love waves within the primary microseism band appear to be mostly generated in different areas, whereas in the secondary microseism band they arrive from similar backazimuths. Furthermore, the <span class="hlt">source</span> areas of surface waves within the secondary microseism band correlate well with modeled deep-water and near-coastal <span class="hlt">source</span> regions.</p> <div class="credits"> <p class="dwt_author">Behr, Y.; Townend, J.; Bowen, M.; Carter, L.; Gorman, R.; Brooks, L.; Bannister, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_11");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" 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showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_14");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">241</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6685818"> <span id="translatedtitle"><span class="hlt">Noise</span> equivalent <span class="hlt">source</span> for frequency domain measurements from the spontaneous fission of /sup 252/Cf</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">An experiment was performed to determine the frequency domain <span class="hlt">noise</span> equivalent <span class="hlt">source</span> from the spontaneous fission of /sup 252/C. The measurements had maximum frequencies (<50 kHz) much lower than those corresponding to the frequencies associated with emission and detection times of particles from spontaneous fission of /sup 252/Cf. This experiment was performed with a /sup 252/Cf <span class="hlt">source</span> on one plate of a parallel-plate ionization chamber and two large plastic scintillators (2 x 1 x 0.33 ft) at distances of 75 to 150 cm from the <span class="hlt">source</span>. This <span class="hlt">noise</span> equivalent <span class="hlt">source</span> is important when using the /sup 252/Cf <span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis method to determine subcriticality at low values of k/sub eff/ (<<0.8) because at low k/sub eff/ values, fluctuations of the neutron population in the system caused by the varying numbers of neutrons from spontaneous fission of /sup 252/Cf become important. The <span class="hlt">noise</span> equivalent <span class="hlt">source</span> for these measurements has been formulated based on the Schottky formalism according to the method of Cohn.</p> <div class="credits"> <p class="dwt_author">Mihalczo, J.T.; King, W.T.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">242</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24181492"> <span id="translatedtitle">Wavepacket <span class="hlt">noise</span> <span class="hlt">source</span> model for microphone array data analysis of hot supersonic jets.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Phased arrays of microphones have proved themselves to be a powerful tool for aeroacoustic investigations. There are many different algorithms for processing the resulting data, including classical beamforming, its modern derivatives, Linear Programming, and Generalized Inverse Methods. The current work stems from a recognition that, for configurations with extended coherent <span class="hlt">sources</span> (such as hot supersonic jets), the Generalized Inverse Method may be preferred, but that its accuracy can be improved by improving the underlying <span class="hlt">source</span> model that it uses. We examine a wavepacket-based <span class="hlt">source</span> model for analysis of the <span class="hlt">noise</span> emitted from hot supersonic jets. This approach provides a more physically realistic representation of the jet <span class="hlt">noise</span> <span class="hlt">sources</span> than previously used. The model is tested using data obtained from numerical simulations as measured at a "virtual" array of microphones. The resulting generalized inverse method analysis is then used to predict <span class="hlt">noise</span> at a farfield arc, and this prediction is compared with that from a conventional Ffowcs Williams-Hawkings acoustic analogy prediction. Initial results with the new wavepacket <span class="hlt">source</span> model are encouraging, with improved directivity predictions and elimination of some spurious <span class="hlt">noise</span> <span class="hlt">sources</span>. The results of the ongoing model development will be included in the final paper. PMID:24181492</p> <div class="credits"> <p class="dwt_author">Morris, Philip; Dougherty, Robert; Nelson, Chris; Cain, Alan; Brentner, Kenneth</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">243</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003MSSP...17..925C"> <span id="translatedtitle">Lyapunov Tuning of the Leaky Lms Algorithm for Single-<span class="hlt">Source</span> Single-Point <span class="hlt">Noise</span> Cancellation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Least-mean square (LMS) algorithms, which are commonly used for adaptive feedforward <span class="hlt">noise</span> cancellation, have performance issues related to insufficient excitation, non-stationary reference inputs, finite-precision arithmetic, quantisation <span class="hlt">noise</span> and measurement <span class="hlt">noise</span>. Such factors cause weight drift and potential instability in the conventional LMS algorithm. Here, we analyse the stability and performance of the leaky LMS algorithm, which is widely used to correct weight drift. A Lyapunov tuning method is developed to find an adaptive leakage parameter and adaptive step size that provide optimum performance and retain stability in the presence of measurement <span class="hlt">noise</span> on the reference input of known variance. The method accounts for non-persistent excitation conditions and non-stationary reference inputs and requires no a priori knowledge of the reference input signal characteristics other than a lower bound on its magnitude or a minimum signal-to-<span class="hlt">noise</span> ratio. The Lyapunov tuning method is demonstrated for three candidate adaptive leakage and step size parameter combinations, each of which is a function of the instantaneous measured reference input, measurement <span class="hlt">noise</span> variance, and/or filter length. These candidates illustrate stability vs performance tradeoffs in the leaky LMS algorithm elicited through the Lyapunov tuning method. The performance of each candidate Lyapunov tuned algorithm is evaluated experimentally in a single <span class="hlt">source</span>, single-point acoustic <span class="hlt">noise</span> cancellation system.</p> <div class="credits"> <p class="dwt_author">Cartes, D. A.; Ray, L. R.; Collier, R. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">244</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22540116"> <span id="translatedtitle">Quantification of <span class="hlt">noise</span> <span class="hlt">sources</span> for amperometric measurement of quantal exocytosis using microelectrodes.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Electrochemical microelectrodes are commonly used to record amperometric spikes of current that result from oxidation of transmitter released from individual vesicles during exocytosis. Whereas the exquisite sensitivity of these measurements is well appreciated, a better understanding of the <span class="hlt">noise</span> <span class="hlt">sources</span> that limit the resolution of the technique is needed to guide the design of next-generation devices. We measured the current power spectral density (S(I)) of electrochemical microelectrodes to understand the physical basis of dominant <span class="hlt">noise</span> <span class="hlt">sources</span> and to determine how <span class="hlt">noise</span> varies with the electrode material and geometry. We find that the current <span class="hlt">noise</span> is thermal in origin in that S(I) is proportional to the real part of the admittance of the electrode. The admittance of microelectrodes is well described by a constant phase element model such that both the real and imaginary admittance increase with frequency raised to a power of 0.84-0.96. Our results demonstrate that the current standard deviation is proportional to the square root of the area of the working electrode, increases ?linearly with the bandwidth of the recording, and varies with the choice of the electrode material with Au ? carbon fiber > nitrogen-doped diamond-like carbon > indium-tin-oxide. Contact between a cell and a microelectrode does not appreciably increase <span class="hlt">noise</span>. Surface-patterned microchip electrodes can have a <span class="hlt">noise</span> performance that is superior to that of carbon-fiber microelectrodes of the same area. PMID:22540116</p> <div class="credits"> <p class="dwt_author">Yao, Jia; Gillis, Kevin D</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-27</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">245</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1991JSV...147..519S"> <span id="translatedtitle">Mechanisms of active <span class="hlt">noise</span> control by vibration <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It is shown how vibration control <span class="hlt">sources</span> can be effectively used in systems designed to actively control structural radiation. Two physical mechanisms are employed: a reduction in structural modal amplitude and/or an alteration in the relative amplitudes and phases of the structured modes. It is noted that the importance of these two mechanisms is a function of various structural/acoustic system parameters.</p> <div class="credits"> <p class="dwt_author">Snyder, S. D.; Hansen, C. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">246</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/t466h406322r8hv5.pdf"> <span id="translatedtitle">Underwater <span class="hlt">noise</span> from maritime <span class="hlt">sources</span> and impact on marine life</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Underwater Sound is essential for marine animal functioning. Sound levels from human <span class="hlt">sources</span> in the marine environment interfere\\u000a with sound-mediated behaviour in marine animals when shipping coincides with areas or pathways that are vital for animal populations.\\u000a The impact of human-generated underwater sound to ecosystem functioning and biodiversity receives increasing attention, although\\u000a as yet it has not been included in</p> <div class="credits"> <p class="dwt_author">Cato C. ten Hallers-Tjabbes</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">247</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21407864"> <span id="translatedtitle">Improving <span class="hlt">noise</span> threshold for optical quantum computing with the EPR photon <span class="hlt">source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We show that the <span class="hlt">noise</span> threshold for optical quantum computing obtained by Varnava et al. [Phys. Rev. Lett. 100, 060502 (2008)] can be significantly improved by replacing the single-photon <span class="hlt">source</span> with the Einstein-Podolsky-Rosen (EPR) type of photon <span class="hlt">source</span>. In this implementation, for an EPR <span class="hlt">source</span> that emits either nothing (a vacuum state) or a perfect EPR state with probability {eta}{sub s}, the detector efficiency {eta}{sub d} is required to be larger than 50% and the <span class="hlt">source</span> efficiency {eta}{sub s} can be an arbitrarily small positive number. We also present the error threshold for a more general <span class="hlt">noise</span> model including additional photon absorption and show that the threshold still compares favorably with the previous results. We discuss several physical setups for realization of the required EPR photon <span class="hlt">source</span>, including a photon emitter in a single-atom cavity.</p> <div class="credits"> <p class="dwt_author">Wei, Z.-H. [Centre for Quantum Technologies, National University of Singapore, Singapore 117542 (Singapore); Department of Physics and MCTP, University of Michigan, Ann Arbor, Michigan 48109 (United States); Han, Y.-J.; Duan, L.-M. [Department of Physics and MCTP, University of Michigan, Ann Arbor, Michigan 48109 (United States); Oh, C. H. [Centre for Quantum Technologies, National University of Singapore, Singapore 117542 (Singapore)</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-06-15</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">248</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1984pad..reptS....W"> <span id="translatedtitle"><span class="hlt">Noise</span> jammer discrimination by <span class="hlt">noise</span> modulation bandwidth</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A method is described for distinguishing between multiple <span class="hlt">noise</span> jammer <span class="hlt">sources</span> having different <span class="hlt">noise</span> modulation bandwidths. <span class="hlt">Noise</span> signals are detected by a receiver having a bandwidth substantially the same as the bandwidth of the jammer <span class="hlt">noise</span> <span class="hlt">source</span>. The dwell time of the <span class="hlt">noise</span> pulses formed by the receiver provides a means for determining the <span class="hlt">noise</span> modulation bandwidth of a <span class="hlt">noise</span> jammer <span class="hlt">source</span>.</p> <div class="credits"> <p class="dwt_author">Wise, C. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">249</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/788041"> <span id="translatedtitle">Further development of low <span class="hlt">noise</span> MEVVA ion <span class="hlt">source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Based on the idea of a space-charge-limited mode of operation, the influence of a pair of electrostatic meshes on the beam parameters of the LBNL MEVVA-5 ion <span class="hlt">source</span> was investigated. The meshes were placed in the expansion zone of the vacuum arc plasma. Apart from reducing the level of beam current fluctuations, this mode of operation provides significant control over the ion charge state distribution of the extracted beam. These effects can be understood taking not only space charge but also the high-directed ion drift velocities into account that are the same for different ion charge states of a material. The results of simulations of the processes involved are in good agreement with the experimental results.</p> <div class="credits"> <p class="dwt_author">Oks, Efim; Yushkov, George; Litovko, Irina; Anders, Andre; Brown, Ian</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-08-28</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">250</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010SPIE.7544E.188W"> <span id="translatedtitle">Method for reducing <span class="hlt">harmonic</span> wave voltage of digital synthetic sine wave</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Developing the ac low voltage standard <span class="hlt">source</span> need the technology of low-<span class="hlt">noise</span> digital synthesis sine wave. In this article, we analysed the frequency spectrum characteristic of the digital synthesis sine wave. Considering the ac low voltage had the strict requirement for <span class="hlt">harmonic</span> wave, we put forward the "<span class="hlt">harmonic</span> wave counteraction method", and found this function to counteract <span class="hlt">harmonic</span> wave, and made it come true from the mathematics and electrocircuit. By the strict calculating of the numerical value and testing verification, we testified the feasibility of the method. By using "<span class="hlt">harmonic</span> wave counteraction method ", every <span class="hlt">harmonic</span> wave <span class="hlt">noise</span> was reduced several order of magnitude, and the total <span class="hlt">noise</span> voltage was less than 4?V in the 50Hz~10kHz frequency range, the uncertainty for the effective value of output voltage was 0.001%.</p> <div class="credits"> <p class="dwt_author">Wang, Bin; Yan, Ming; Pan, Pan; Feng, Wenwu</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">251</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18665176"> <span id="translatedtitle">An equivalent-<span class="hlt">source</span> model for simulating <span class="hlt">noise</span> generation in turbofan engines</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Nowadays, computational aeroacoustics (CAA) is used for simulating wave propagation in ducted turbofans, especially as computational fluid dynamics (CFD) is increasingly employed to model the identified <span class="hlt">noise</span> <span class="hlt">sources</span>. An efficient way to match the CFD and CAA domains is to make some assumptions on flow and duct geometry, so that disturbance fields can be expanded over incoming\\/outgoing acoustic modes. Based</p> <div class="credits"> <p class="dwt_author">C. Polacsek; G. Desquesnes; G. Reboul</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">252</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://flab.eng.isas.ac.jp/member/nonomura/top_j/publications/data/Okamoto2008.pdf"> <span id="translatedtitle">Computational Analysis of <span class="hlt">Noise</span> <span class="hlt">Sources</span> inside The High Speed Flow over a Generalized Bump</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The aerodynamic <span class="hlt">noise</span> <span class="hlt">sources</span> around a three dimensional bump are studied. Firstly in this paper, validation of the numerical method with ILES using symmetric bump is discussed. Cp distribution on the bump is discussed and ILES simulation result shows good agreement with Visbal's numerical result 1 . The gradient of spanwise velocity fluctuation spectrum of present result agrees with gradient</p> <div class="credits"> <p class="dwt_author">Kentaro Okamoto; Taku Nonomura; Kozo Fujii</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">253</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N20080047422"> <span id="translatedtitle">Time Delay Analysis of Turbofan Engine Direct and Indirect Combustion <span class="hlt">Noise</span> <span class="hlt">Sources</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The core <span class="hlt">noise</span> components of a dual spool turbofan engine were separated by the use of a coherence function. A <span class="hlt">source</span> location technique based on adjusting the time delay between the combustor pressure sensor signal and the far-field microphone signal to ...</p> <div class="credits"> <p class="dwt_author">J. H. Miles</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">254</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50397739"> <span id="translatedtitle">Reduced spatially correlated <span class="hlt">noise</span> influence using subspace <span class="hlt">source</span> localization method FINES</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We have developed a high resolution subspace approach for EEG <span class="hlt">source</span> localization within a realistic geometry inhomogeneous head model. The present study aims to reduce the influence caused by spatially correlated <span class="hlt">noise</span> from background activities using FINES. Computer simulations were conducted on the realistic geometry head volume conductor model and compared with the classic MUSIC algorithm. The FINES approach was</p> <div class="credits"> <p class="dwt_author">Lei Ding; Xiaoliang Xu; Bobby Xu; Ying Ni; Bin He</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">255</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ksem.eti.pg.gda.pl/pta/referaty11/listewnik.pdf"> <span id="translatedtitle">THE EXAMINATION OF POSITION OF SHIP'S <span class="hlt">NOISES</span> <span class="hlt">SOURCES</span> BASED ON HYDROACOUSTICS METHOD</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The paper presents the experimental research associated with the transmission of acoustic energy generated by moving ship into the water. The paper present the methodology of evaluations acoustics energy from the mechanisms of ship into the water environment. For that purpose the research of <span class="hlt">noise</span> distribution over ship's hull were conducted along with the hydroacoustic field. The hull is <span class="hlt">source</span></p> <div class="credits"> <p class="dwt_author">KAROL LISTEWNIK</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">256</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18608059"> <span id="translatedtitle">Numerical calculation for determining sonar self <span class="hlt">noise</span> <span class="hlt">sources</span> due to structural vibration</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">It is important to determine dominant sonar self <span class="hlt">noise</span> <span class="hlt">sources</span> on a ship due to structural vibration. Much computation time is required for conventional simulation methods like BEM because it needs matrix inversion to determine the sound pressure on the radiating surface. In this paper, the simplified simulation method which reduces the calculation by using a vibro-acoustic transfer function is</p> <div class="credits"> <p class="dwt_author">Takaaki Musha; Tatsuo Kikuchi</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">257</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1546880"> <span id="translatedtitle">Theory of linewidth for multielectrode laser diodes with spatially distributed <span class="hlt">noise</span> <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A general theory of linewidth for single-frequency semiconductor lasers is presented. The effects of spatially distributed <span class="hlt">noise</span> <span class="hlt">sources</span> together with spatially varying carrier and photon densities and injection current are analyzed in a rigorous manner by solution of the scalar wave equation. A new rate equation for the electric field is derived, in which the longitudinal effects are represented in</p> <div class="credits"> <p class="dwt_author">Bjarne Tromborg; Henning Olesen; Xing Pan</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">258</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26170023"> <span id="translatedtitle">Influence of measurement <span class="hlt">noise</span> and electrode mislocalisation on EEG dipole-<span class="hlt">source</span> localisation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Measurement <span class="hlt">noise</span> in the electro-encephalogram (EEG) and inaccurate formation about the locations of the EEG electrodes on\\u000a the head induce localisation errors in the results of EEG dipole <span class="hlt">source</span> analysis. These errors are studied by performing dipole\\u000a <span class="hlt">source</span> localisation for simulated electrode potentials in a spherical head model, for a range of different dipole locations\\u000a and for two different numbers</p> <div class="credits"> <p class="dwt_author">G. Van Hoey; B. Vanrumste; M. D'Havé; R. Van de Walle; I. Lemahieu; P. Boon</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">259</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1982PhDT........88W"> <span id="translatedtitle">Experimental and Analytical Studies of Shielding Concepts for Point <span class="hlt">Sources</span> and Jet <span class="hlt">Noises</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This analytical and experimental study explores concepts for jet <span class="hlt">noise</span> shielding. Model experiments centre on solid planar shields, simulating engine-over-wing installations, and 'sugar scoop' shields. Tradeoff on effective shielding length is set by interference 'edge <span class="hlt">noise</span>' as the shield trailing edge approaches the spreading jet. Edge <span class="hlt">noise</span> is minimized by (i) hyperbolic cutouts which trim off the portions of most intense interference between the jet flow and the barrier and (ii) hybrid shields--a thermal refractive extension (a flame); for (ii) the tradeoff is combustion <span class="hlt">noise</span>. In general, shielding attenuation increases steadily with frequency, following low frequency enhancement by edge <span class="hlt">noise</span>. Although broadband attenuation is typically only several dB, the reduction of the subjectively weighted perceived <span class="hlt">noise</span> levels is higher. In addition, calculated ground contours of peak PN dB show a substantial contraction due to shielding: this reaches 66% for one of the 'sugar scoop' shields for the 90 PN dB contour. The experiments are complemented by analytical predictions. They are divided into an engineering scheme for jet <span class="hlt">noise</span> shielding and more rigorous analysis for point <span class="hlt">source</span> shielding. The former approach combines point <span class="hlt">source</span> shielding with a suitable jet <span class="hlt">source</span> distribution. The results are synthesized into a predictive algorithm for jet <span class="hlt">noise</span> shielding: the jet is modelled as a line distribution of incoherent <span class="hlt">sources</span> with narrow band frequency (TURN)(axial distance)('-1). The predictive version agrees well with experiment (1 to 1.5 dB) up to moderate frequencies. The insertion loss deduced from the point <span class="hlt">source</span> measurements for semi-infinite as well as finite rectangular shields agrees rather well with theoretical calculation based on the exact half plane solution and the superposition of asymptotic closed-form solutions. An approximate theory, the Maggi-Rubinowicz line integral, is found to yield reasonable predictions for thin barriers including cutouts if a certain correction is applied. The more exact integral equation approach (solved numerically) is applied to a more demanding geometry: a half round sugar scoop shield. It is found that the solutions of integral equation derived from Helmholtz formula in normal derivative form show satisfactory agreement with measurements.</p> <div class="credits"> <p class="dwt_author">Wong, Raymond Lee Man</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">260</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23464008"> <span id="translatedtitle">Mapping underwater sound <span class="hlt">noise</span> and assessing its <span class="hlt">sources</span> by using a self-organizing maps method.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">This study aims to provide an objective mapping of the underwater <span class="hlt">noise</span> and its <span class="hlt">sources</span> over an Adriatic coastal marine habitat by applying the self-organizing maps (SOM) method. Systematic sampling of sea ambient <span class="hlt">noise</span> (SAN) was carried out at ten predefined acoustic stations between 2007 and 2009. Analyses of <span class="hlt">noise</span> levels were performed for 1/3 octave band standard centered frequencies in terms of instantaneous sound pressure levels averaged over 300 s to calculate the equivalent continuous sound pressure levels. Data on vessels' presence, type, and distance from the monitoring stations were also collected at each acoustic station during the acoustic sampling. Altogether 69 <span class="hlt">noise</span> surveys were introduced to the SOM predefined 2 × 2 array. The overall results of the analysis distinguished two dominant underwater soundscapes, associating them mainly to the seasonal changes in the nautical tourism and fishing activities within the study area and to the wind and wave action. The analysis identified recreational vessels as the dominant anthropogenic <span class="hlt">source</span> of underwater <span class="hlt">noise</span>, particularly during the tourist season. The method demonstrated to be an efficient tool in predicting the SAN levels based on the vessel distribution, indicating also the possibility of its wider implication for marine conservation. PMID:23464008</p> <div class="credits"> <p class="dwt_author">Rako, Nikolina; Vilibi?, Ivica; Mihanovi?, Hrvoje</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-03-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_12");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' 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id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_13");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return 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src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">261</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/36166850"> <span id="translatedtitle">Characterization of the Myosin-Based <span class="hlt">Source</span> for Second-<span class="hlt">Harmonic</span> Generation from Muscle Sarcomeres</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Several biologically important protein structures give rise to strong second-<span class="hlt">harmonic</span> generation (SHG) in their native context. In addition to high-contrast optical sections of cells and tissues, SHG imaging can provide detailed structural information based on the physical constraints of the optical effect. In this study we characterize, by biochemical and optical analysis, the critical structures underlying SHG from the complex</p> <div class="credits"> <p class="dwt_author">Sergey V. Plotnikov; Andrew C. Millard; Paul J. Campagnola; William A. Mohler</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">262</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EPJST.187..179N"> <span id="translatedtitle">Spontaneous dynamics and response properties of a Hodgkin-Huxley-type neuron model driven by <span class="hlt">harmonic</span> synaptic <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We study statistical properties, response dynamics, and information transmission in a Hodgkin-Huxley-type neuron system, modeling peripheral electroreceptors in paddlefish. In addition to sodium and potassium currents, the neuron model includes fast calcium and slow afterhyperpolarization (AHP) potassium currents. The synaptic transmission from sensory epithelium is modeled by a Poission process with a rate modulated by narrow-band <span class="hlt">noise</span>, mimicking stochastic epithelial oscillations observed experimentally. We study how the interplay of parameters of AHP current and synaptic <span class="hlt">noise</span> affects the statistics of spontaneous dynamics and response properties of the system. In particular, we confirm predictions made earlier with perfect integrate and fire and phase neuron models that epithelial oscillations enhance stimulus-response coherence and thus information transmission in electroreceptor system. In addition, we consider a strong stimulus regime and show that coherent epithelial oscillations may reduce variability of electroreceptor responses to time-varying stimuli.</p> <div class="credits"> <p class="dwt_author">Nguyen, H.; Neiman, A. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">263</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004PhDT.......119T"> <span id="translatedtitle">Low-frequency <span class="hlt">noise</span> <span class="hlt">sources</span> in III-V semiconductor heterostructures</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">III-V semiconductor heterostructures have widespread interest in both electrical and optical applications. Their figure-of-merit low-frequency <span class="hlt">noise</span> level directly sets the limits of the performance of devices and indirectly serves as the indicator of material properties and device reliability. In particular, generation-recombination <span class="hlt">noise</span> signals in the low-frequency <span class="hlt">noise</span> range directly indicate the dominant traps that impact device operation. In this dissertation, low-frequency <span class="hlt">noise</span> <span class="hlt">source</span> investigations of GaAs/buffer and AlxGa1-xN/GaN heterostructures in the applications of microwave power amplifiers will be presented. For GaAs/buffer heterostructures, low-frequency <span class="hlt">noise</span> characteristics of GaAs-On-Insulator metal-semiconductor field effect transistors, for which the insulating buffer layer was produced by lateral wet-oxidation of AlAs, are studied. Devices with different gate widths were fabricated resulting in different over-oxidation times for the AlAs layer. Three characteristic generation-recombination <span class="hlt">noise</span> signatures are observed depending on the measurement temperature and the gate bias. A generation-recombination <span class="hlt">noise</span> signature with energy level at Ec-0.69 eV is found to increase with the amount of over-oxidation time. This near mid-gap trap shows an increase in concentration towards the oxide interface, and it is tentatively assigned to an arsenic-antisite related defect known from previous studies as EB4. A possible mechanism for the formation and the microscopic origin of this defect are discussed. 1/f interface <span class="hlt">noise</span> model is applied to analyze the GaAs/buffer interfacial quality. The effective interface state density was found to be as high as 1015 cm-2 and increase with additional over-oxidation. A correlation between the amount of over-oxidation and the number of calculated interface states is observed. For AlxGa1-xN/GaN heterostructures, low-frequency <span class="hlt">noise</span> characteristics of AlxGa1-xN/GaN HEMTs with Al composition of 28--35% in the barrier layer are studied. A generation-recombination <span class="hlt">noise</span> signature is attributed to a trap in AlxGa1-x N barrier layer which increases in concentration towards the Al xGa1-xN/GaN interface. The origin and the location of low-frequency <span class="hlt">noise</span> were differentiated by the drain current dependent measurement. When the long-channel device is operated with an open channel (e.g. VG = 0), the main <span class="hlt">noise</span> <span class="hlt">source</span> resides in the gated channel instead of in the ungated region. Hooge's parameter of the gated channel (alpha ˜ 10-4) is found to be independent of the Al composition but dependent on the AlxGa1-x N barrier thickness. This is proposed to correspond to the onset of barrier relaxation. Even though the AlxGa1-xN/GaN HEMT exhibits a low level of gate leakage current (<1% of drain current), the low-frequency <span class="hlt">noise</span> is still heavily influenced by the gate leakage current at certain bias conditions. The effect of gate leakage current on the low-frequency <span class="hlt">noise</span> properties is discussed. The surface leakage path appeared to dominate the low-frequency <span class="hlt">noise</span> properties for devices operated at a high IG/ID ratio.</p> <div class="credits"> <p class="dwt_author">Tzeng, Susie</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">264</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011PhDT.......106D"> <span id="translatedtitle">Supersonic jet <span class="hlt">noise</span> prediction and <span class="hlt">noise</span> <span class="hlt">source</span> investigation for realistic baseline and chevron nozzles based on hybrid RANS/LES simulations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Jet <span class="hlt">noise</span> simulations have been performed for a military-style baseline nozzle and a chevron nozzle with design Mach numbers of Md = 1:5 operating at several off-design conditions. The objective of the current numerical study is to provide insight into the <span class="hlt">noise</span> generation mechanisms of shock-containing supersonic hot jets and the <span class="hlt">noise</span> reduction mechanisms of chevron nozzles. A hybrid methodology combining advanced CFD technologies and the acoustic analogy is used for supersonic jet <span class="hlt">noise</span> simulations. Unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved to predict the turbulent <span class="hlt">noise</span> <span class="hlt">sources</span> in the jet flows. A modified version of the Detached Eddy Simulation (DES) approach is used to avoid excessive damping of fine scale turbulent fluctuations. A multiblock structured mesh topology is used to represent complex nozzle geometries, including the faceted inner contours and finite nozzle thickness. A block interface condition is optimized for the complex multiblock mesh topology to avoid the centerline singularity. A fourth-order Dispersion-Relation-Preserving (DRP) scheme is used for spatial discretization. To enable efficient calculations, a dual time-stepping method is used in addition to parallel computation using MPI. Both multigrid and implicit residual smoothing are used to accelerate the convergence rate of sub-iterations in the fictitious time domain. <span class="hlt">Noise</span> predictions are made with the permeable surface Ffowcs Williams and Hawkings (FWH) solution. All the numerical methods have been implemented in the jet flow simulation code "CHOPA" and the <span class="hlt">noise</span> prediction code "PSJFWH". The computer codes have been validated with several benchmark cases. A preliminary study has been performed for an under-expanded baseline nozzle jet with Mj = 1:56 to validate the accuracy of the jet <span class="hlt">noise</span> simulations. The results show that grid refinement around the jet potential core and the use of a lower artificial dissipation improve the resolution of the predicted high frequency <span class="hlt">noise</span> spectra. The results also show that the predicted low frequency <span class="hlt">noise</span> spectra are sensitive to the axial extent of the acoustic data surface, and the high frequency <span class="hlt">noise</span> spectra are affected by the radial size of the acoustic data surface. The baseline nozzle has been studied at several off-design conditions with Mj = 1:36, 1.47 and 1.56. Although the <span class="hlt">noise</span> levels at mid to high frequencies are over-predicted at several shallow polar angles, the predicted <span class="hlt">noise</span> spectra in the peak <span class="hlt">noise</span> radiation direction and upstream directions agree very well with the experimental measurements. More encouraging is that the frequencies and amplitudes of the broadband shock-associated <span class="hlt">noise</span> (BBSAN) are captured accurately at all three operating conditions. Three techniques are used to examine the <span class="hlt">noise</span> <span class="hlt">source</span> characteristics. The two-point space-time correlation method is used to analyze the statistical characteristics of the turbulent eddies. The direct flow-acoustic correlation technique and the beamformed acoustic pressures are used to reveal the different <span class="hlt">noise</span> generation mechanisms of the large-scale and fine-scale turbulent fluctuations. The chevron nozzle simulations have been performed at the same operating conditions to evaluate the <span class="hlt">noise</span> reduction effects. Special treatments are proposed to address the numerical difficulties caused by the chevrons. The impact of chevrons on the near-field <span class="hlt">noise</span> <span class="hlt">sources</span> and far-field <span class="hlt">noise</span> radiation is simulated using the immersed boundary method (IBM) to overcome the great difficulties in grid generation. A non-matching block interface condition is developed to allow the grids to be greatly refined around chevrons for a higher accuracy of simulations without increasing the mesh size significantly. The predicted <span class="hlt">noise</span> spectra agree very well with the acoustic measurements of the baseline nozzle, considering the small <span class="hlt">noise</span> reductions of the chevrons at the given operating conditions. No apparent over-prediction is observed. However, the <span class="hlt">noise</span> reductions are over-predicted because of the over-pr</p> <div class="credits"> <p class="dwt_author">Du, Yongle</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">265</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23556597"> <span id="translatedtitle">Localizing the <span class="hlt">sources</span> of two independent <span class="hlt">noises</span>: role of time varying amplitude differences.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Listeners localized the free-field <span class="hlt">sources</span> of either one or two simultaneous and independently generated <span class="hlt">noise</span> bursts. Listeners' localization performance was better when localizing one rather than two sound <span class="hlt">sources</span>. With two sound <span class="hlt">sources</span>, localization performance was better when the listener was provided prior information about the location of one of them. Listeners also localized two simultaneous <span class="hlt">noise</span> bursts that had sinusoidal amplitude modulation (AM) applied, in which the modulation envelope was in-phase across the two <span class="hlt">source</span> locations or was 180° out-of-phase. The AM was employed to investigate a hypothesis as to what process listeners might use to localize multiple sound <span class="hlt">sources</span>. The results supported the hypothesis that localization of two sound <span class="hlt">sources</span> might be based on temporal-spectral regions of the combined waveform in which the sound from one <span class="hlt">source</span> was more intense than that from the other <span class="hlt">source</span>. The interaural information extracted from such temporal-spectral regions might provide reliable estimates of the sound <span class="hlt">source</span> location that produced the more intense sound in that temporal-spectral region. PMID:23556597</p> <div class="credits"> <p class="dwt_author">Yost, William A; Brown, Christopher A</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">266</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27082910"> <span id="translatedtitle">Beacon-Aided Adaptive Localization of <span class="hlt">Noise</span> <span class="hlt">Sources</span> Aboard a Pass-By Railcar Using a Trackside Microphone Array</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A new adaptive “beamforming” signal-processing algorithm is developed to locate the loudest <span class="hlt">noise</span> <span class="hlt">sources</span> aboard a railcar that passes by a trackside immobile microphone array. This proposed microphone-array beamformer tracks the railcar's spatial movement with the aid of two inaudible acoustic beacons placed aboard the railcar. The proposed scheme then localizes the <span class="hlt">noise</span> <span class="hlt">sources</span> with reference to the railcar's coordinates.</p> <div class="credits"> <p class="dwt_author">Yue Ivan Wu; Siu-Kit Lau; Kainam Thomas Wong; Shiu-Keung Tang</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">267</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50035823"> <span id="translatedtitle">Tomographical reconstruction of oceanic inhomogeneities. 1. Forming partially coherent acoustic wave structures in the ocean with spatially localized <span class="hlt">noise</span> <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The formation and features of partially coherent acoustical waves excited by spatially localized <span class="hlt">noise</span> <span class="hlt">sources</span> are investigated in this work. It is shown that nonuniform distributions of the parameters of partially coherent waves in oceanic waveguides appear due to inhomogeneities of oceanic environments. Physical models of spatially localized <span class="hlt">noise</span> <span class="hlt">sources</span>, such as ships, are developed. Analysis and calculations show that</p> <div class="credits"> <p class="dwt_author">Ivan P. Smirnov; A. I. Khil'ko; J. W. Caruthers</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">268</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009JSV...320..726T"> <span id="translatedtitle">Active control of <span class="hlt">noise</span> on the <span class="hlt">source</span> side of a partition to increase its sound isolation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This paper describes a local active <span class="hlt">noise</span> control system that virtually increases the sound isolation of a dividing wall by means of a secondary <span class="hlt">source</span> array. With the proposed method, sound pressure on the <span class="hlt">source</span> side of the partition is reduced using an array of loudspeakers that generates destructive interference on the wall surface, where an array of error microphones is placed. The reduction of sound pressure on the incident side of the wall is expected to decrease the sound radiated into the contiguous room. The method efficiency was experimentally verified by checking the insertion loss of the active <span class="hlt">noise</span> control system; in order to investigate the possibility of using a large number of actuators, a decentralized FXLMS control algorithm was used. Active control performances and stability were tested with different array configurations, loudspeaker directivities and enclosure characteristics (sound <span class="hlt">source</span> position and absorption coefficient). The influence of all these parameters was investigated with the factorial design of experiments. The main outcome of the experimental campaign was that the insertion loss produced by the secondary <span class="hlt">source</span> array, in the 50-300 Hz frequency range, was close to 10 dB. In addition, the analysis of variance showed that the active <span class="hlt">noise</span> control performance can be optimized with a proper choice of the directional characteristics of the secondary <span class="hlt">source</span> and the distance between loudspeakers and error microphones.</p> <div class="credits"> <p class="dwt_author">Tarabini, Marco; Roure, Alain; Pinhede, Cedric</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">269</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AIPC.1086..452S"> <span id="translatedtitle">Multi-MW K-Band <span class="hlt">Harmonic</span> Multiplier: RF <span class="hlt">Source</span> For High-Gradient Accelerator R & D</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A preliminary design is presented for a two-cavity <span class="hlt">harmonic</span> multiplier, intended as a high-power RF <span class="hlt">source</span> for use in experiments aimed at developing high-gradient structures for a future collider. The <span class="hlt">harmonic</span> multiplier is to produce power at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE111 rotating mode input cavity and interchangeable output cavities running in the TEn11 rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7th <span class="hlt">harmonic</span> multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.</p> <div class="credits"> <p class="dwt_author">Solyak, N. A.; Yakovlev, V. P.; Kazakov, S. Yu.; Hirshfield, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">270</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21255263"> <span id="translatedtitle">Multi-MW K-Band <span class="hlt">Harmonic</span> Multiplier: RF <span class="hlt">Source</span> For High-Gradient Accelerator R and D</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A preliminary design is presented for a two-cavity <span class="hlt">harmonic</span> multiplier, intended as a high-power RF <span class="hlt">source</span> for use in experiments aimed at developing high-gradient structures for a future collider. The <span class="hlt">harmonic</span> multiplier is to produce power at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE{sub 111} rotating mode input cavity and interchangeable output cavities running in the TE{sub n11} rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7{sup th} <span class="hlt">harmonic</span> multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.</p> <div class="credits"> <p class="dwt_author">Solyak, N. A.; Yakovlev, V. P. [Omega-P, Inc., 199 Whitney Ave., New Haven, CT 06511 (United States); Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kazakov, S. Yu. [Omega-P, Inc., 199 Whitney Ave., New Haven, CT 06511 (United States); High Energy Accelerator Research Organization, KEK, Tsukuba, Ibaraki 305-0801 Japan (Japan); Hirshfield, J. L. [Omega-P, Inc., 199 Whitney Ave., New Haven, CT 06511 (United States); Beam Physics Laboratory, Yale University, 272 Whitney Avenue, New Haven, CT 06511 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-22</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">271</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1985bbn..rept.....H"> <span id="translatedtitle">Methods for designing treatments to reduce interior <span class="hlt">noise</span> of predominant <span class="hlt">sources</span> and paths in a single engine light aircraft</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">sources</span> and paths by which <span class="hlt">noise</span> enters the cabin of a small single engine aircraft were determined through a combination of flight and laboratory tests. The primary <span class="hlt">sources</span> of <span class="hlt">noise</span> were found to be airborne <span class="hlt">noise</span> from the propeller and engine casing, airborne <span class="hlt">noise</span> from the engine exhaust, structureborne <span class="hlt">noise</span> from the engine/propeller combination and <span class="hlt">noise</span> associated with air flow over the fuselage. For the propeller, the primary airborne paths were through the firewall, windshield and roof. For the engine, the most important airborne path was through the firewall. Exhaust <span class="hlt">noise</span> was found to enter the cabin primarily through the panels in the vicinity of the exhaust outlet although exhaust <span class="hlt">noise</span> entering the cabin through the firewall is a distinct possibility. A number of <span class="hlt">noise</span> control techniques were tried, including firewall stiffening to reduce engine and propeller airborne <span class="hlt">noise</span>, to stage isolators and engine mounting spider stiffening to reduce structure-borne <span class="hlt">noise</span>, and wheel well covers to reduce air flow <span class="hlt">noise</span>.</p> <div class="credits"> <p class="dwt_author">Hayden, Richard E.; Remington, Paul J.; Theobald, Mark A.; Wilby, John F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">272</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005QJRMS.131.2151N"> <span id="translatedtitle">Can error <span class="hlt">source</span> terms in forecasting models be represented as Gaussian Markov <span class="hlt">noises</span>?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The repercussions of model error on the long term climatological means and on the variability around them are analysed. The extent to which a stochastic representation of error <span class="hlt">source</span> terms provides a universal correcting mechanism is addressed. General relations are derived linking the model error to the climatological means and the variability properties of a forecasting model subjected to a correcting Gaussian Markov <span class="hlt">noise</span> on the basis of moment equations associated with Fokker-Planck and Liouville type equations. These relations are implemented in a variety of models giving rise to regular and to chaotic solutions. As it turns out, forecasting models fall into distinct universality classes differing in their response to the effect of <span class="hlt">noise</span> according to the structure of the Jacobian and the Hessian matrices of the model phase-space velocity. It is concluded that different trends may exist in which the 'correcting' <span class="hlt">noise</span> tends to depress or, on the contrary, amplify the model error.</p> <div class="credits"> <p class="dwt_author">Nicolis, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">273</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011NJPh...13i3003L"> <span id="translatedtitle">Shot-to-shot and average absolute photon flux measurements of a femtosecond laser high-order <span class="hlt">harmonic</span> photon <span class="hlt">source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The absolute flux of a femtosecond vacuum-ultraviolet (VUV) photon <span class="hlt">source</span> based on the high-order <span class="hlt">harmonic</span> generation of a femtosecond Ti:sapphire laser and monochromatized with a grating monochromator is determined both on a shot-to-shot basis and averaged over seconds by a calibrated gas monitor detector. The average flux is compared with the average flux as determined with a calibrated GaAsP semiconductor photodiode. We found that the photodiode is a reliable and easy-to-use tool for estimating the order of magnitude of the average photon flux but that, due to saturation losses, it underestimates the average flux by up to -15%.</p> <div class="credits"> <p class="dwt_author">Leitner, T.; Sorokin, A. A.; Gaudin, J.; Kaser, H.; Kroth, U.; Tiedtke, K.; Richter, M.; Wernet, Ph</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">274</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013GeoJI.tmp..527H"> <span id="translatedtitle">Measurements and kernels for <span class="hlt">source</span>-structure inversions in <span class="hlt">noise</span> tomography</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Seismic <span class="hlt">noise</span> cross-correlations are used to image crustal structure and heterogeneity. Typically, seismic networks are anisotropically illuminated by seismic <span class="hlt">noise</span>, a consequence of the non-uniform distribution of <span class="hlt">sources</span>. Here, we study the sensitivity of such a seismic network to structural heterogeneity in a 2-D setting. We compute finite-frequency cross-correlation sensitivity kernels for traveltime, waveform-energy and waveform-difference measurements. In line with expectation, wave speed anomalies are best imaged using traveltimes and the <span class="hlt">source</span> distribution using cross-correlation energies. Perturbations in attenuation and impedance are very difficult to image and reliable inferences require a high degree of certainty in the knowledge of the <span class="hlt">source</span> distribution and wave speed model (at least in the case of transmission tomography studied here). We perform single-step Gauss-Newton inversions for the <span class="hlt">source</span> distribution and the wave speed, in that order, and quantify the associated Cramér-Rao lower bound. The inversion and uncertainty estimate are robust to errors in the <span class="hlt">source</span> model but are sensitive to the theory used to interpret of measurements. We find that when classical <span class="hlt">source</span>-receiver kernels are used instead of cross-correlation kernels, errors appear in the both the inversion and uncertainty estimate, systematically biasing the results. We outline a computationally tractable algorithm to account for distant <span class="hlt">sources</span> when performing inversions.</p> <div class="credits"> <p class="dwt_author">Hanasoge, Shravan M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">275</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50766279"> <span id="translatedtitle">Effect of leakage inductance on high frequency transformer <span class="hlt">harmonics</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Nowadays, switching power supplies are used in almost all electronic devices to regulate the voltage amplitude. The only obstacle on using these devices is the production of high frequency <span class="hlt">harmonics</span> that violates different standards such as (FCC, VDE, 461). In this paper the <span class="hlt">sources</span> of various <span class="hlt">noises</span> in switching power supplies will be introduced. Then, using appropriate model for high</p> <div class="credits"> <p class="dwt_author">Babak Abdi; Mohammad Hadi Joukar; Amir Hossein Ranjbar</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">276</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007APS..MARH32010N"> <span id="translatedtitle">Dynamics of particle density and <span class="hlt">noise</span> correlators of a cold Fermi system expanding from a <span class="hlt">harmonic</span> trap</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We have studied dynamics of an atomic Fermi system with a finite number of particles N after it is released from a <span class="hlt">harmonic</span> trapping potential. We consider two different initial states: the Fermi sea state and the projected BCS (PBCS) state described by the projection of the grand-canonical BCS wave function onto the subspace with a fixed number of particles. In the former case, we derive exact and simple analytic expressions for the particle density n(r,t) and density-density correlation functions <n(r,t) n(r',t)> taking into account the level quantization and possible anisotropy of the trap. In the latter case of the PBCS state, we obtain analytic expressions for the density and its correlators in the leading order with respect to the ratio of the trap frequency and the superconducting gap (the ratio assumed small). We discuss several interesting dynamic features, which may be used to distinguish between the Fermi sea and BCS states.</p> <div class="credits"> <p class="dwt_author">Nagornykh, Pavel; Galitski, Victor</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">277</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1980aiaa.confR....F"> <span id="translatedtitle">A collection of formulas for calculation of rotating blade <span class="hlt">noise</span> - Compact and noncompact <span class="hlt">source</span> results</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A unified approach is used to derive many of the current formulations for calculation of discrete frequency <span class="hlt">noise</span> for helicopter rotors and propellers. Both compact and noncompact <span class="hlt">source</span> formulations are derived. The compact formulations are obtained as the limit of noncompact <span class="hlt">source</span> results. In particular, the linearized acoustic equations by Hawkings and Lowson, Farassat, Hanson, Woan and Gregorek, Succi, and Jou are derived in this paper. An interesting thickness <span class="hlt">noise</span> formula by Isom and its recent extension to the near field by Ffowcs Williams are also presented. The paper includes some comparisons of measured and calculated acoustic pressure signatures and spectra for an advanced propeller. The theoretical results are obtained using a computer program developed by the author and P. A. Nystrom.</p> <div class="credits"> <p class="dwt_author">Farassat, F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">278</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5647253"> <span id="translatedtitle">Dynamic subcriticality measurements using the /sup 252/Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> method</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This paper describes dynamic measurements of the subcritical neutron multiplication factor using the /sup 252/Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis method for a tank containing uranyl nitrate solution. These experiments are part of a program of collaboration between the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan to study criticality safety related to the development of fast breeder technology.</p> <div class="credits"> <p class="dwt_author">Mihalczo, J.T.; Blakeman, E.D.; Ragan, G.E.; Johnson, E.B.; Seino, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">279</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/61371131"> <span id="translatedtitle">Dynamic subcriticality measurements using the ²⁵²Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> method</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper describes dynamic measurements of the subcritical neutron multiplication factor using the ²⁵²Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis method for a tank containing uranyl nitrate solution. These experiments are part of a program of collaboration between the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan to study criticality safety related to the development of</p> <div class="credits"> <p class="dwt_author">J. T. Mihalczo; E. D. Blakeman; G. E. Ragan; E. B. Johnson; H. Seino</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">280</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005APhy...51..609A"> <span id="translatedtitle">Active <span class="hlt">noise</span> cancellation of a spherical multipole <span class="hlt">source</span> using a radially vibrating spherical baffled piston</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The creation of quiet zones in a diffuse sound field due to a multipole spherical primary <span class="hlt">source</span> by means of a radially vibrating surface set in the side of a rigid sphere (secondary <span class="hlt">source</span>) is investigated in this article. The formulation utilizes the appropriate wave field expansions along with the translational addition theorems for spherical wave functions to develop a closed-form solution in the form of an infinite series. The numerical results reveal that using a baffled spherical piston model as a secondary <span class="hlt">source</span> instead of a monopole control <span class="hlt">source</span> will obviously improve the sound minimization efficiency of such <span class="hlt">noise</span>-control systems in all cases, especially for a dipolar primary <span class="hlt">source</span>.</p> <div class="credits"> <p class="dwt_author">Azarpeyvand, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-11-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return 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onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_16");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">281</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23988431"> <span id="translatedtitle">Improved PHIP polarization using a precision, low <span class="hlt">noise</span>, voltage controlled current <span class="hlt">source</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Existing para-hydrogen induced polarization (PHIP) instrumentation relies on magnetic fields to hyperpolarize substances. These hyperpolarized substances have enhanced magnetic resonance imaging (MRI) signals over 10,000 fold, allowing for MRI at the molecular level. Required magnetic fields are generated by energizing a solenoid coil with current produced by a voltage controlled voltage <span class="hlt">source</span> (VCVS), also known as a power supply. A VCVS lacks the current regulation necessary to keep magnetic field fluctuations to a minimum, which results in low PHIP polarization. A voltage controlled current <span class="hlt">source</span> (VCCS) is an electric circuit that generates a steady flow of electrons proportional to an input voltage. A low <span class="hlt">noise</span> VCCS provides the solenoid current flow regulation necessary to generate a stable static magnetic field (Bo). We discuss the design and implementation of a low <span class="hlt">noise</span>, high stability, VCCS for magnetic field generation with minimum variations. We show that a precision, low <span class="hlt">noise</span>, voltage reference driving a metal oxide semiconductor field effect transistor (MOSFET) based current sink, results in the current flow control necessary for generating a low <span class="hlt">noise</span> and high stability Bo. In addition, this work: (1) compares current stability for ideal VCVS and VCCS models using transfer functions (TF), (2) develops our VCCS design's TF, (3) measures our VCCS design's thermal & 1/f <span class="hlt">noise</span>, and (4) measures and compares hydroxyethyl-propionate (HEP) polarization obtained using a VCVS and our VCCS. The hyperpolarization of HEP was done using a PHIP instrument developed in our lab. Using our VCCS design, HEP polarization magnitude data show a statistically significant increase in polarization over using a VCVS. Circuit schematic, bill of materials, board layout, TF derivation, and Matlab simulations code are included as supplemental files. PMID:23988431</p> <div class="credits"> <p class="dwt_author">Agraz, Jose; Grunfeld, Alexander; Cunningham, Karl; Li, Debiao; Wagner, Shawn</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-12</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">282</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013JMagR.235...77A"> <span id="translatedtitle">Improved PHIP polarization using a precision, low <span class="hlt">noise</span>, voltage controlled current <span class="hlt">source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Existing para-hydrogen induced polarization (PHIP) instrumentation relies on magnetic fields to hyperpolarize substances. These hyperpolarized substances have enhanced magnetic resonance imaging (MRI) signals over 10,000 fold, allowing for MRI at the molecular level. Required magnetic fields are generated by energizing a solenoid coil with current produced by a voltage controlled voltage <span class="hlt">source</span> (VCVS), also known as a power supply. A VCVS lacks the current regulation necessary to keep magnetic field fluctuations to a minimum, which results in low PHIP polarization. A voltage controlled current <span class="hlt">source</span> (VCCS) is an electric circuit that generates a steady flow of electrons proportional to an input voltage. A low <span class="hlt">noise</span> VCCS provides the solenoid current flow regulation necessary to generate a stable static magnetic field (Bo). We discuss the design and implementation of a low <span class="hlt">noise</span>, high stability, VCCS for magnetic field generation with minimum variations. We show that a precision, low <span class="hlt">noise</span>, voltage reference driving a metal oxide semiconductor field effect transistor (MOSFET) based current sink, results in the current flow control necessary for generating a low <span class="hlt">noise</span> and high stability Bo. In addition, this work: (1) compares current stability for ideal VCVS and VCCS models using transfer functions (TF), (2) develops our VCCS design's TF, (3) measures our VCCS design's thermal & 1/f <span class="hlt">noise</span>, and (4) measures and compares hydroxyethyl-propionate (HEP) polarization obtained using a VCVS and our VCCS. The hyperpolarization of HEP was done using a PHIP instrument developed in our lab. Using our VCCS design, HEP polarization magnitude data show a statistically significant increase in polarization over using a VCVS. Circuit schematic, bill of materials, board layout, TF derivation, and Matlab simulations code are included as supplemental files.</p> <div class="credits"> <p class="dwt_author">Agraz, Jose; Grunfeld, Alexander; Cunningham, Karl; Li, Debiao; Wagner, Shawn</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">283</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/20000811"> <span id="translatedtitle">Reduction of electromagnetic force <span class="hlt">harmonics</span> in asynchronous traction motor by adapting the rotor slot number</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The <span class="hlt">harmonics</span> in electromagnetic force are <span class="hlt">source</span> of the mechanical vibration and the audible <span class="hlt">noise</span> in an asynchronous traction motor. This paper describes an approach to reduce the force <span class="hlt">harmonics</span> by changing the rotor slot number. Both the radial and tangential forces acting on the stator teeth are calculated by Maxwell stress tenser and their time <span class="hlt">harmonics</span> are examined by the discrete Fourier decomposition. As a result, the optimal slot number of the rotor to reduce or eliminate the specific force <span class="hlt">harmonics</span> is determined.</p> <div class="credits"> <p class="dwt_author">Kim, B.T.; Kwon, B.I.; Park, S.C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">284</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/19506682"> <span id="translatedtitle">High-brightness, low-<span class="hlt">noise</span>, all-fiber photon pair <span class="hlt">source</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We demonstrate an all-fiber photon pair <span class="hlt">source</span> for the critical telecom C-band. We achieve high pair generation rates in excess of 10 MHz while maintaining coincidence-to-accidental ratios (CARs) greater than 100. This is one of the brightest and lowest-<span class="hlt">noise</span> photon pair <span class="hlt">sources</span> ever demonstrated. We achieve the high pair rate through CW-pumped spontaneous four-wave mixing in dispersion-shifted fiber. We achieve the high CAR by cooling the fiber to 4 K to suppress the Raman generation and detecting the photons with low jitter and low dark count superconducting single-photon detectors. PMID:19506682</p> <div class="credits"> <p class="dwt_author">Dyer, Shellee D; Baek, Burm; Nam, Sae Woo</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">285</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50160035"> <span id="translatedtitle">A cross-relation based matched field processor for <span class="hlt">source</span> localization with random <span class="hlt">noise</span> <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper presents a cross-relation (CR) based matched field processing (MFP) technique for <span class="hlt">source</span> localization in a shallow water environment where the <span class="hlt">source</span> propagates a random signal. The estimation formulas are given for nonstationary (NS) and wide sense stationary (WSS) random <span class="hlt">sources</span>. For each case two formulations are proposed, a self-CR and a cross-CR according to which channel output signal</p> <div class="credits"> <p class="dwt_author">Reza M. Dizaji; N. Ross Chapman; R. Lynn Kirlin</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">286</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/1035153"> <span id="translatedtitle">Non-Uniform Contrast and <span class="hlt">Noise</span> Correction for Coded <span class="hlt">Source</span> Neutron Imaging</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Since the first application of neutron radiography in the 1930s, the field of neutron radiography has matured enough to develop several applications. However, advances in the technology are far from concluded. In general, the resolution of scintillator-based detection systems is limited to the $10\\mu m$ range, and the relatively low neutron count rate of neutron <span class="hlt">sources</span> compared to other illumination <span class="hlt">sources</span> restricts time resolved measurement. One path toward improved resolution is the use of magnification; however, to date neutron optics are inefficient, expensive, and difficult to develop. There is a clear demand for cost-effective scintillator-based neutron imaging systems that achieve resolutions of $1 \\mu m$ or less. Such imaging system would dramatically extend the application of neutron imaging. For such purposes a coded <span class="hlt">source</span> imaging system is under development. The current challenge is to reduce artifacts in the reconstructed coded <span class="hlt">source</span> images. Artifacts are generated by non-uniform illumination of the <span class="hlt">source</span>, gamma rays, dark current at the imaging sensor, and system <span class="hlt">noise</span> from the reconstruction kernel. In this paper, we describe how to pre-process the coded signal to reduce <span class="hlt">noise</span> and non-uniform illumination, and how to reconstruct the coded signal with three reconstruction methods correlation, maximum likelihood estimation, and algebraic reconstruction technique. We illustrates our results with experimental examples.</p> <div class="credits"> <p class="dwt_author">Santos-Villalobos, Hector J [ORNL; Bingham, Philip R [ORNL</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">287</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012SPIE.8296E..14S"> <span id="translatedtitle">Non-uniform contrast and <span class="hlt">noise</span> correction for coded <span class="hlt">source</span> neutron imaging</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Since the first application of neutron radiography in the 1930s, the field of neutron radiography has matured enough to develop several applications. However, advances in the technology are far from concluded. In general, the resolution of scintillator-based detection systems is limited to the 10?m range, and the relatively low neutron count rate of neutron <span class="hlt">sources</span> compared to other illumination <span class="hlt">sources</span> restricts time resolved measurement. One path toward improved resolution is the use of magnification; however, to date neutron optics are inefficient, expensive, and difficult to develop. There is a clear demand for cost-effective scintillator-based neutron imaging systems that achieve resolutions of 1?m or less. Such imaging system would dramatically extend the application of neutron imaging. For such purposes a coded <span class="hlt">source</span> imaging system is under development. The current challenge is to reduce artifacts in the reconstructed coded <span class="hlt">source</span> images. Artifacts are generated by non-uniform illumination of the <span class="hlt">source</span>, gamma rays, dark current at the imaging sensor, and system <span class="hlt">noise</span> from the reconstruction kernel. In this paper, we describe how to pre-process the coded signal to reduce <span class="hlt">noise</span> and non-uniform illumination, and how to reconstruct the coded signal with three reconstruction methods correlation, maximum likelihood estimation, and algebraic reconstruction technique. We illustrates our results with experimental examples.</p> <div class="credits"> <p class="dwt_author">Santos-Villalobos, Hector J.; Bingham, Philip R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">288</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009JSV...323..697P"> <span id="translatedtitle">An equivalent-<span class="hlt">source</span> model for simulating <span class="hlt">noise</span> generation in turbofan engines</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Nowadays, computational aeroacoustics (CAA) is used for simulating wave propagation in ducted turbofans, especially as computational fluid dynamics (CFD) is increasingly employed to model the identified <span class="hlt">noise</span> <span class="hlt">sources</span>. An efficient way to match the CFD and CAA domains is to make some assumptions on flow and duct geometry, so that disturbance fields can be expanded over incoming/outgoing acoustic modes. Based on this approach, this paper presents an original matching model in which the outgoing modes are generated by means of equivalent monopole distributions defined as <span class="hlt">source</span> terms in the equations governing the acoustic propagation, instead of a conventional inflow boundary condition (BC). Advantages and limits of the method are discussed. The process to get back to the <span class="hlt">sources</span> and its numerical implementing are described. Although initially focused on tones, an extension of the method to broadband <span class="hlt">noise</span> generation is tackled too. The method then is validated on a simplified turbofan exhaust configuration. Numerical solutions obtained by implementing the <span class="hlt">source</span> terms in a high-order time-domain Euler code are compared to analytical solutions, either in a uniform or in a radially shear mean flow (provided by RANS). The parallel shear flow solution is obtained by solving the Pridmore-Brown equation. The ability to accurately simulate the standing waves due to acoustic reflections at duct ends is also assessed by comparing the numerical solutions computed using both <span class="hlt">source</span>-based and BC-based options in the Euler solver.</p> <div class="credits"> <p class="dwt_author">Polacsek, C.; Desquesnes, G.; Reboul, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">289</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AIPC.1495..242C"> <span id="translatedtitle">A perspective on 30 years of progress in ambient <span class="hlt">noise</span>: <span class="hlt">Source</span> mechanisms and the characteristics of the sound field</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The last 30 years has seen substantial progress in ocean ambient <span class="hlt">noise</span> research, particularly in understanding the mechanisms of sound generation by the <span class="hlt">sources</span> of ambient <span class="hlt">noise</span>, the way in which the <span class="hlt">noise</span> field is affected by sound propagation, and improvements in quantifying the relationship between <span class="hlt">noise</span> and environmental parameters. This has led to significant improvements in <span class="hlt">noise</span> prediction. Activity was probably strongest in the 1980s and 1990s, as evident, for example, in the Sea Surface Sound conferences and their published proceedings (four over 10 years). Although much of the application has been to sonar, there has also been interest in using ambient <span class="hlt">noise</span> to measure properties of the environment and in its significance to marine life. There have been significant changes in the ambient <span class="hlt">noise</span> itself over the last 30 years. The contribution from human activities appears to have increased, particularly that due to increases in shipping numbers. Biological <span class="hlt">noise</span> has also increased with the significant increases in populations of some whale species following the cessation of broad scale whaling in the 1960s and early 1970s. Concern about the effects of <span class="hlt">noise</span> on marine animals as well as the way they exploit the <span class="hlt">noise</span> has led to renewed interest in ambient <span class="hlt">noise</span>.</p> <div class="credits"> <p class="dwt_author">Cato, Douglas H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">290</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22978868"> <span id="translatedtitle"><span class="hlt">Noise</span> suppression of a dipole <span class="hlt">source</span> by tensioned membrane with side-branch cavities.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Reducing the ducted-fan <span class="hlt">noise</span> at the low frequency range remains a big technical challenge. This study presents a passive approach to directly suppress the dipole sound radiation from an axial-flow fan housed by a tensioned membrane with cavity backing. The method aims at achieving control of low frequency <span class="hlt">noise</span> with an appreciable bandwidth. The use of the membrane not only eliminates the aerodynamic loss of flow, but also provides flexibility in controlling the range of the stopband with high insertion loss by varying its tension and mass. A three-dimensional model is presented which allows the performance of the proposed device to be explored analytically. With the proper design, this device can achieve a <span class="hlt">noise</span> reduction of 5 dB higher than the empty expansion cavity recently proposed by Huang et al. [J. Acoust. Soc. Am. 128, 152-163 (2010)]. Through the detailed modal analysis, even in vacuo modes of the membrane vibration are found to play an important role in the suppression of sound radiation from the dipole <span class="hlt">source</span>. Experimental validation is conducted with a loudspeaker as the dipole <span class="hlt">source</span> and good agreement between the predicted and measured insertion loss is achieved. PMID:22978868</p> <div class="credits"> <p class="dwt_author">Liu, Y; Choy, Y S; Huang, L; Cheng, L</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">291</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1982SoPh...77..249S"> <span id="translatedtitle">Positions of type II fundamental and <span class="hlt">harmonic</span> <span class="hlt">sources</span> in the 30-100 MHZ range</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">An excellent example of a type III-V burst followed by a type II burst with fundamental and <span class="hlt">harmonic</span> bands was observed on June 18, 1979 at the Clark Lake Radio Observatory. The observations are described in detail and their implications are discussed with regard to the problem of directionality with respect to the magnetic field lines of the collisionless MHD shock wave generated at the start of the flash phase. It is found that the positions of type III and type II (F) bursts at a number of frequencies are essentially the same, which implies that the shock responsible for the type II radiation follows the path of the type III exciter, that is, the shock propagates along the open field lines.</p> <div class="credits"> <p class="dwt_author">Sawant, H. S.; Gergely, T. E.; Kundu, M. R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">292</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22109124"> <span id="translatedtitle">Ultrahigh 22 nm resolution coherent diffractive imaging using a desktop 13 nm high <span class="hlt">harmonic</span> <span class="hlt">source</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">New diffractive imaging techniques using coherent x-ray beams have made possible nanometer-scale resolution imaging by replacing the optics in a microscope with an iterative phase retrieval algorithm. However, to date very high resolution imaging (< 40 nm) was limited to large-scale synchrotron facilities. Here, we present a significant advance in image resolution and capabilities for desktop soft x-ray microscopes that will enable widespread applications in nanoscience and nanotechnology. Using 13 nm high <span class="hlt">harmonic</span> beams, we demonstrate a record 22 nm spatial resolution for any tabletop x-ray microscope. Finally, we show that unique information about the sample can be obtained by extracting 3-D information at very high numerical apertures. PMID:22109124</p> <div class="credits"> <p class="dwt_author">Seaberg, Matthew D; Adams, Daniel E; Townsend, Ethan L; Raymondson, Daisy A; Schlotter, William F; Liu, Yanwei; Menoni, Carmen S; Rong, Lu; Chen, Chien-Chun; Miao, Jianwei; Kapteyn, Henry C; Murnane, Margaret M</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">293</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004RScI...75.2541L"> <span id="translatedtitle">Low-<span class="hlt">noise</span> computer-controlled current <span class="hlt">source</span> for quantum coherence experiments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We describe a dual current <span class="hlt">source</span> designed to provide static flux biases for a superconducting qubit and for the Superconducting QUantum Interference Device (SQUID) which measures the qubit state. The <span class="hlt">source</span> combines digitally programmable potentiometers with a stabilized voltage <span class="hlt">source</span>. Each channel has a maximum output of +/-1 mA, and can be adjusted with an accuracy of about +/-1 nA. Both current supplies are fully computer controlled and designed not to inject digital <span class="hlt">noise</span> into the quantum bit and SQUID during manipulation and measurement of the flux. For a 275 ?A setting, the measured <span class="hlt">noise</span> current is 2.6 parts per million (ppm) rms, in a bandwidth of 0.0017-10 Hz, from which we estimate dephasing times of hundreds of nanoseconds in the particular case of our own qubit design. By resetting the current every 10 min, we are able to reduce the drift to no more than 5 ppm at a current of 750 ?A over a period of 3 days. The current <span class="hlt">source</span> has been implemented without thermal regulation inside a radiofrequency-shielding room, and is used routinely in our quantum coherence experiments.</p> <div class="credits"> <p class="dwt_author">Linzen, S.; Robertson, T. L.; Hime, T.; Plourde, B. L. T.; Reichardt, P. A.; Clarke, John</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">294</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013JSV...332.6276E"> <span id="translatedtitle">In-situ <span class="hlt">source</span> path contribution analysis of structure borne road <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Source</span>-path-contribution (SPC) analysis, also known as transfer path analysis (TPA), is a technique widely used in the automotive industry for rank ordering <span class="hlt">noise</span> and vibration <span class="hlt">sources</span>. The SPC approach is known to provide reliable diagnostic information but is time consuming to apply. In this paper, a faster SPC approach that allows all measurements to be performed in-situ is outlined and tested. For validation purposes a classic example consisting of a vehicle's suspension system (considered a vibration <span class="hlt">source</span>) attached to a vehicle body (receiver) is analysed. It is found that structure borne <span class="hlt">noise</span> inside the vehicle can be predicted well by either the conventional or the novel in-situ SPC approaches and that both methods give the same diagnostic information in terms of the rank ordering of path contributions. Thus, the new in-situ approach provides results at least as reliable as the conventional inverse SPC approach but has significant practical advantages in terms of reduced test time, transferability of data and flexibility in the location of the <span class="hlt">source</span>-receiver interface. An additional investigation also demonstrates the feasibility of including rotational motions and moments in the analysis and it is shown that improved accuracy can be achieved as a result.</p> <div class="credits"> <p class="dwt_author">Elliott, A. S.; Moorhouse, A. T.; Huntley, T.; Tate, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">295</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006APS..DFD.KN006H"> <span id="translatedtitle">Identification and Control of <span class="hlt">Noise</span> <span class="hlt">Source</span> Mechanisms in a Transonic Axisymmetric Jet</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">An experimental examination aimed at characterizing the aeroacoustic effect linked to the turbulent mixing of the exhausted jet plume with the ambient air in high-speed jets is comprised of a 50.8mm nozzle at Mach 0.85, operated under both heated (260oC) and room temperature (0oC) conditions. Both the hydrodynamic near- field and acoustic far-field pressure regions are examined. The near- field using an azimuthal array of fifteen (15) dynamic response pressure transducers positioned near the jet’s lip, and the far- field using a boom array of six (6) acoustic microphones (6.35mm in diameter). Instantaneous 3 component velocity measurements are acquired, simultaneously, in the r, theta plane at several streamwise positions between z/D=3:8 (the region where the sound producing events are found to be dominant) using a stereo PIV system. This data set is utilized in conjunction with multi-point low-dimensional techniques to characterize a low-dimensional description of the velocity field, with minimal effect on far-field acoustics. The low- dimensional description of the velocity field is examined to identify the dominant <span class="hlt">noise</span> <span class="hlt">source</span> mechanism in both jets. Calculation of a modified Lighthill <span class="hlt">source</span> term, and azimuthal modal forcing, are used as a measure of <span class="hlt">source</span> intensity and a gauge for <span class="hlt">noise</span> reduction schemes, respectively. Where control of <span class="hlt">noise</span> <span class="hlt">sources</span> is concerned, a modal analysis of the near-field region has shown that modal forcing may prove a promising method. We greatly acknowledge the support of the AFOSR and the CNY-PR AGEP Alliance.</p> <div class="credits"> <p class="dwt_author">Hall, Andre; Pinier, Jeremy; Glauser, Mark</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">296</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011JGRA..116.3104S"> <span id="translatedtitle">Constraints on coronal turbulence models from <span class="hlt">source</span> sizes of <span class="hlt">noise</span> storms at 327 MHz</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We seek to reconcile observations of small <span class="hlt">source</span> sizes in the solar corona at 327 MHz with predictions of scattering models that incorporate refractive index effects, inner scale effects, and a spherically diverging wavefront. We use an empirical prescription for the turbulence amplitude CN2(R) based on very long baseline interferometry observations by Spangler et al. of compact radio <span class="hlt">sources</span> against the solar wind for heliocentric distances R ? 10-50 R?. We use the Coles and <span class="hlt">Harmon</span> model for the inner scale li(R), which is presumed to arise from cyclotron damping. In view of the prevalent uncertainty in the power law index that characterizes solar wind turbulence at various heliocentric distances, we retain this index as a free parameter. We find that the inclusion of spherical divergence effects suppresses the predicted <span class="hlt">source</span> size substantially. We also find that inner scale effects significantly reduce the predicted <span class="hlt">source</span> size. An important general finding for solar <span class="hlt">sources</span> is that the calculations substantially underpredict the observed <span class="hlt">source</span> size. Three possible, nonexclusive, interpretations of this general result are proposed. First and simplest, future observations with better angular resolution will detect much smaller <span class="hlt">sources</span>. Consistent with this, previous observations of small <span class="hlt">sources</span> in the corona at metric wavelengths are limited by the instrument resolution. Second, the spatially varying level of turbulence CN2(R) is much larger in the inner corona than predicted by straightforward extrapolation sunward of the empirical prescription, which was based on observations between 10 and 50 R?. Either the functional form or the constant of proportionality could be different. Third, perhaps the inner scale is smaller than the model, leading to increased scattering. These results and interpretations are discussed and compared with earlier work.</p> <div class="credits"> <p class="dwt_author">Subramanian, Prasad; Cairns, Iver</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">297</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADD011224"> <span id="translatedtitle"><span class="hlt">Noise</span> Jammer Discrimination by <span class="hlt">Noise</span> Spectral Bandwidth.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">A method for distinguishing between multiple <span class="hlt">noise</span> jammer <span class="hlt">sources</span> having different <span class="hlt">noise</span> spectral bandwidths. <span class="hlt">Noise</span> signals are detected over a relatively narrow detection bandwidth. The percent of time that the jammer spectral <span class="hlt">noise</span> is within the fixed d...</p> <div class="credits"> <p class="dwt_author">C. D. Wise</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">298</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22418499"> <span id="translatedtitle">Extreme ultraviolet light <span class="hlt">source</span> based on intracavity high <span class="hlt">harmonic</span> generation in a mode locked Ti:sapphire oscillator with 9.4 MHz repetition rate.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We report on the realization of an intracavity high <span class="hlt">harmonic</span> <span class="hlt">source</span> with a cutoff above 30 eV. The EUV <span class="hlt">source</span> is based on a high power, hard-aperture, Kerr-lens mode-locked Ti:sapphire oscillator with a repetition rate of 9.4 MHz. The laser is operated in the net negative dispersion regime resulting in intracavity pulses as short as 17 fs with 1 µJ pulse energy. In a second intracavity focus, intensity more than 10¹? W/cm² has been achieved, which is sufficient for high <span class="hlt">harmonic</span> generation in a Xenon gas jet. PMID:22418499</p> <div class="credits"> <p class="dwt_author">Seres, Enikoe; Seres, Jozsef; Spielmann, Christian</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-03-12</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">299</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013SuMi...63..110G"> <span id="translatedtitle">Modulation of excitation kinetics of impurity doped quantum dots by the interplay between confinement <span class="hlt">sources</span> and multiplicative Gaussian white <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We investigate the excitation kinetics of a repulsive impurity doped quantum dot initiated by the application of multiplicative Gaussian white <span class="hlt">noise</span>. The <span class="hlt">noise</span> strength and the dot confinement <span class="hlt">sources</span> of electric and magnetic origin have been found to produce the said kinetics in a subtle way. In addition to this the dopant location also plays some crucial role. The present study sheds light on how the individual or combined variation of different confinement <span class="hlt">sources</span> could design the excitation kinetics in presence of <span class="hlt">noise</span>. The investigation reveals maximization and saturation in the excitation kinetics as a result of complex interplay between the confinement potentials of the dot, the dopant location, and the <span class="hlt">noise</span> strength. The present investigation is believed to provide some useful perceptions of the functioning of mesoscopic systems where <span class="hlt">noise</span> plays some profound role.</p> <div class="credits"> <p class="dwt_author">Ganguly, Jayanta; Pal, Suvajit; Ghosh, Manas</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">300</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22214544"> <span id="translatedtitle">Improving AFM images with <span class="hlt">harmonic</span> interference by spectral analysis.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Atomic force microscopy (AFM) is one of the most sensitive tools for nanoscale imaging. As such, it is very sensitive to external <span class="hlt">noise</span> <span class="hlt">sources</span> that can affect the quality of collected data. The intensity of the disturbance depends on the <span class="hlt">noise</span> <span class="hlt">source</span> and the mode of operation. In some cases, the internal <span class="hlt">noise</span> from commercial AFM controllers can be significant and difficult to remove. Thus, a new method based on spectrum analysis of the scanned images is proposed to reduce <span class="hlt">harmonic</span> disturbances. The proposal is a post-processing method and can be applied at any time after measurements. This article includes a few methods of <span class="hlt">harmonic</span> cancellation (e.g., median filtering, wavelet denoising, Savitzky-Golay smoothing) and compares their effectiveness. The proposed method, based on Fourier transform of the scanned images, was more productive than the other methods mentioned before. The presented data were achieved for images of conductive layers taken in a contact AFM mode. PMID:22214544</p> <div class="credits"> <p class="dwt_author">Kiwilszo, Marek; Zieli?ski, Artur; Smulko, Janusz; Darowicki, Kazimierz</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-04</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_14");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return 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class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_15");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return 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title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">301</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013JSV...332.6093T"> <span id="translatedtitle">Analysis on the frequency-domain numerical method to compute the <span class="hlt">noise</span> radiated from rotating <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A frequency-domain solution of the Ffowcs Williams-Hawkings equation with a penetrable data surface is presented for the thickness, loading and quadrupole <span class="hlt">noise</span> to avoid the singularities that exist in the time-domain methods. Since this method is based on the numerical integration over <span class="hlt">source</span> time, there is no need to solve the retarded-time equation or to perform the interpolation on time-domain data, and the time-domain <span class="hlt">source</span> information obtained by modern CFD codes can be utilized directly. The acoustic pressure spectra of monopole, dipole and quadrupole point <span class="hlt">sources</span> in subsonic and supersonic rotation are calculated with the presented method, and the results agree well with those obtained by the retarded-time method and frequency-domain analytical method.</p> <div class="credits"> <p class="dwt_author">Tang, Hongtao; Qi, Datong; Mao, Yijun</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">302</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1985adap.agar.....S"> <span id="translatedtitle">Application of active <span class="hlt">noise</span> control to model propeller <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The applicability of active <span class="hlt">noise</span> control to reduce cabin <span class="hlt">noise</span> of turboprop aircraft is demonstrated by conducting several laboratory experiments. The principle of active <span class="hlt">noise</span> control is to reduce the <span class="hlt">noise</span> radiated from a primary <span class="hlt">source</span> by superimposing a signal from a secondary <span class="hlt">source</span>, which is made identical in amplitude but opposite in phase to the primary sound signal. A computer controlled algorithm was developed to implement this concept in a free field environment, in which, the <span class="hlt">noise</span> from the primary <span class="hlt">source</span> (eventually the propeller) and the <span class="hlt">noise</span> measured at several locations on a representative surface (eventually the fuselage) were used to create the input for the secondary <span class="hlt">source</span>. Experiments using a number of sinusoidal signals were conducted. An average <span class="hlt">noise</span> reduction of 8 to 14 dB was achieved on the surface in the frequency range of 200 to 1000 Hz. Next the concept was applied to the propeller problem where the sound signal contains many discrete tones at <span class="hlt">harmonics</span> of the blade passage frequency. For this purpose, a prerecorded time history of a 1/10th scale model propeller was used to drive the primary <span class="hlt">source</span>. An average <span class="hlt">noise</span> reduction of about 15 dB was observed at the first two blade passage frequencies, and 12 dB and 5 dB reductions were observed at the 3rd and 4th blade passage frequencies, respectively. Finally, the active <span class="hlt">noise</span> control concept was applied to a 1/10th scale propeller, installed in an anechoic chamber with flight simulation facility. A substantial amount of <span class="hlt">noise</span> reduction was achieved on the model fuselage surface.</p> <div class="credits"> <p class="dwt_author">Salikuddin, M.; Tanna, H. K.; Burrin, R. H.; Carter, W. E.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-02-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">303</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011APS..DFDM18005L"> <span id="translatedtitle"><span class="hlt">Noise</span> <span class="hlt">source</span> characterization from far-field data in high-speed jets</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We analyze pressure data from 3 microphones in the far-field coherent <span class="hlt">noise</span> cone of a Ma=0.6 jet. 3500 individual <span class="hlt">sources</span> are identified in the time-frequency domain, and some of their properties are extracted from the wavelet coefficients: magnitude, frequency, time of arrival. The <span class="hlt">sources</span>' signature therefore includes the lags between the sound arrival times at the microphones. Based on a modeled mean jet velocity field, we calculate the refracted acoustic paths and propagation times from a grid of <span class="hlt">source</span> locations to the microphones. The excellent agreement between measured and calculated lags provides a mapping between the measured lags and the approximate <span class="hlt">source</span> locations. For our catalog of <span class="hlt">sources</span>, we report on some statistics of <span class="hlt">source</span> properties as a function of their location in the near-jet's shear layer and developing region beyond the end of the potential core. The ability to narrow the search (time and location) for <span class="hlt">sources</span> in near-field data (LES or PIV) may be established on this basis.</p> <div class="credits"> <p class="dwt_author">Lewalle, Jacques; Low, Kerwin R.; Glauser, Mark N.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">304</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55820475"> <span id="translatedtitle">Determination of <span class="hlt">noise</span> <span class="hlt">source</span> heights, part II: Measurement of the equivalent <span class="hlt">source</span> height of highway vehicles</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This is the second of two companion papers which describe the measurement of the equivalent point <span class="hlt">source</span> height on highway vehicles. The first paper describes the measurement method, and the second its application to highway vehicles. This paper discusses the measurements on moving highway vehicles. First it is shown how the measurement method is suitable for measuring the equivalent point</p> <div class="credits"> <p class="dwt_author">S. A. L. Glegg; J. R. Yoon</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">305</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/10107515"> <span id="translatedtitle">Skew <span class="hlt">harmonics</span> suppression in electromagnets with application to the Advanced Light <span class="hlt">Source</span> (ALS) storage ring corrector magnet design</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">An analytical expression for prediction of skew <span class="hlt">harmonics</span> in an iron core combined function regular/skew dipole magnet due to arbitrarily positioned electromagnet coils is developed. A structured approach is presented for the suppression of an arbitrary number of <span class="hlt">harmonic</span> components to arbitrarily low values. Application of the analytical <span class="hlt">harmonic</span> strength calculations coupled to the structured <span class="hlt">harmonic</span> suppression approach is presented in the context of the design of the ALS storage ring corrector magnets, where quadrupole, sextupole, and octupole skew <span class="hlt">harmonics</span> were reduced to less than 1.0% of the skew dipole at the beam aperture radius r = 3.0 cm.</p> <div class="credits"> <p class="dwt_author">Schlueter, R.; Halbach, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">306</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/5665180"> <span id="translatedtitle">Subcritical measurements using the /sup 252/Cf <span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis method</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This paper describes recent measurements of the subcritical neutron multiplication factor using the /sup 252/Cf <span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis method. This work was supported by a program of collaboration between the United States Department of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan related to the development of fast breeder technology. The experiment reported consists of a configuration of two interacting tanks of uranyl nitrate aqueous solution with different uranium concentrations in each tank. The /sup 252/Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis method obtains the subcriticality from the signals of three detectors: the first, a parallel plate ionization chamber with /sup 252/Cf electroplated on one of its plates that is located in or near the system containing the fissile material, and produces an electrical pulse for every spontaneous fission that occurs and thereby serves as a timed <span class="hlt">source</span> of fission neutrons; and the second and third detectors that are placed in or near the system containing fissile material and serve to detect particles from the fission chain multiplication process. 9 refs.</p> <div class="credits"> <p class="dwt_author">Mihalczo, J.T.; Blakeman, E.D.; Ragan, G.E.; Kryter, R.C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">307</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1367074"> <span id="translatedtitle">Characterization of the Myosin-Based <span class="hlt">Source</span> for Second-<span class="hlt">Harmonic</span> Generation from Muscle Sarcomeres</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Several biologically important protein structures give rise to strong second-<span class="hlt">harmonic</span> generation (SHG) in their native context. In addition to high-contrast optical sections of cells and tissues, SHG imaging can provide detailed structural information based on the physical constraints of the optical effect. In this study we characterize, by biochemical and optical analysis, the critical structures underlying SHG from the complex muscle sarcomere. SHG emission arises from domains of the sarcomere containing thick filaments, even within nascent sarcomeres of differentiating myocytes. SHG from isolated myofibrils is abolished by extraction of myosin, but is unaffected by removal or addition of actin filaments. Furthermore, the polarization dependence of sarcomeric SHG is not affected by either the proportion of myosin head domains or the orientation of myosin heads. By fitting SHG polarization anisotropy readings to theoretical response curves, we find an orientation for the elemental harmonophore that corresponds well to the pitch of the myosin rod ?-helix along the thick filament axis. Taken together, these data indicate that myosin rod domains are the key structures giving SHG from striated muscle. This study should guide the interpretation of SHG contrast in images of cardiac and skeletal muscle tissue for a variety of biomedical applications.</p> <div class="credits"> <p class="dwt_author">Plotnikov, Sergey V.; Millard, Andrew C.; Campagnola, Paul J.; Mohler, William A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">308</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26968414"> <span id="translatedtitle">Power Factor Correction Based on Transmission Loss Minimization with Uncertain <span class="hlt">Source</span> <span class="hlt">Harmonics</span> and Load Characteristics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This article presents a method of reducing the expected value of the transmission loss for a specified range of <span class="hlt">source</span> impedance values at different buses by using inductor-capacitor compensators where it is desired to maintain a given power factor at a specified value. The criterion is based on mean value estimation of <span class="hlt">source</span> and load characteristics, which is enabled by</p> <div class="credits"> <p class="dwt_author">O. M. Aloquili; A. F. Zobaa; H. H. Zeineldin</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">309</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/21456743"> <span id="translatedtitle">Low <span class="hlt">noise</span> K?-band hopping reflectometer based on yttrium iron garnet <span class="hlt">sources</span> at TEXTOR.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The heterodyne hopping reflectometer system based on wide-tuned low <span class="hlt">noise</span> yttrium iron garnet <span class="hlt">sources</span> was developed for TEXTOR experiment. Being installed in 1998 it successfully operates more than 10 years providing the measurements of plasma density fluctuations. Owing to the advance multihorn antennae systems installed at three different positions around the tokamak, the correlation properties as well as the propagation measurements of plasma density fluctuations are realized. The reflectometer operates in ordinary polarization mode providing the access mostly to plasma gradient and pedestal region. The capabilities of the diagnostic are illustrated with the examples of measured fluctuation characteristics in the variety of TEXTOR plasmas. PMID:21456743</p> <div class="credits"> <p class="dwt_author">Soldatov, S; Krämer-Flecken, A; Zorenko, O</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">310</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1998SPIE.3378..123S"> <span id="translatedtitle">Microwave active cold/warm <span class="hlt">noise</span> <span class="hlt">source</span> for calibration of radiometer sensors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">For most radiometers, periodic calibration is essential to ensure sensor measurement accuracy. This paper describes the application of a unique active microwave circuit that simulates known radiated thermal temperatures over a stepped range of less than 105 K to over 300 K. The device, when connected or switched to the input of a receiver, can be incrementally stepped via a bias voltage from the coldest to the warmest temperature. It offers the potential to replace more complex and expensive external and internal calibration techniques. In addition to calibration, the device also serves to test the receiver linearity and measure receiver <span class="hlt">noise</span> figure. The paper will identify significant advances in the area of modeling, design, development, and test of the stepped 'cold/warm' <span class="hlt">noise</span> <span class="hlt">source</span>. Several prototype FET circuits, using 150 and 300 micrometer InP devices, have been built and demonstrated at K-band frequencies of 18 - 22 GHz. Work is in progress to build and test the next device at 37 GHz. Tests have been conducted at Raytheon Systems, the University of South Florida (USF), and the National Institute of Science and Technology (NIST). The results illustrate good agreement between simulation and measurements. Block diagrams are included to show the method of calibrating radiometers, testing receiver linearity, and measuring receiver <span class="hlt">noise</span> figure.</p> <div class="credits"> <p class="dwt_author">Smith, Matthew C.; Roeder, Robert S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">311</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1988JSV...127..485I"> <span id="translatedtitle">Annoyance due to mixed <span class="hlt">source</span> <span class="hlt">noises</span>- A laboratory study and field surve on the annoyance of road traffic and railroad <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The purpose of this study is twofold. The first is to validate the usefulness of the simulated environment method for the assessment of community responses, and the second is to validate the annoyance models so far proposed for the evaluation of mixed <span class="hlt">source</span> <span class="hlt">noise</span>. The study comprised a laboratory study and a field survey, both designed on the same principle. In the Simulated Living Room laboratory at Muroran Institute of Technology (MTEC), subjects were exposed to the various combinations of road traffic and railroad <span class="hlt">noises</span>, and their responses to the total and the <span class="hlt">source</span> specific annoyance were collected. The field study was carried out in the vicinity of Muroran City, where both a railroad line and a heavy traffic road pass through. Residents were interviewed and questionnaires with the key questions regarding community and domestic annoyance were collected. After the interviews, 24 h measurements of road traffic and railroad <span class="hlt">noises</span> were made. Finally, the dose-response relations obtained both in the laboratory study and the field study were compared. A good similarity was discovered in the findings by the two approaches, which suggested the usefulness of the simulated environment method. With the findings obtained, seven annoyance models so far proposed for the evaluation of mixed <span class="hlt">source</span> <span class="hlt">noise</span> were examined.</p> <div class="credits"> <p class="dwt_author">Izumi, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">312</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56461404"> <span id="translatedtitle">Prediction of potential <span class="hlt">noise</span> interactions in axial-flow machines - Application to the helicopter fenestron</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A method for predicting the far-field <span class="hlt">noise</span> created in a rotor by the flow around cylindrical obstacles (such as support arms) placed downstream of the rotor is proposed. Application of the method to helicopter rotor blades shows that this <span class="hlt">noise</span> <span class="hlt">source</span> can account for the fundamental and first <span class="hlt">harmonics</span> of the blade frequencies. It is suggested that higher frequences may</p> <div class="credits"> <p class="dwt_author">Francette Fournier; Michel Roger</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">313</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/11931298"> <span id="translatedtitle">An ensemble <span class="hlt">source</span> spectra model for merchant ship-radiated <span class="hlt">noise</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">This paper presents an evaluation of the classical model for determining an ensemble of the broadband <span class="hlt">source</span> spectra of the sound generated by individual ships and proposes an alternate model to overcome the deficiencies in the classical model. The classical model, proposed by Ross [Mechanics of Underwater <span class="hlt">Noise</span> (Pergamon, New York, 1976)] postulates that the <span class="hlt">source</span> spectrum for an individual ship is proportional to a baseline spectrum with the constant of proportionality determined by a power-law relationship on the ship speed and length. The model evaluation, conducted on an ensemble of 54 <span class="hlt">source</span> spectra over a 30-1200-Hz to 1200-Hz frequency band, shows that this assumption yields large rms errors in the broadband <span class="hlt">source</span> level for the individual ships and significantly overestimates the variability in the <span class="hlt">source</span> level across the ensemble of <span class="hlt">source</span> spectra. These deficiencies are a consequence of the negligible correlation between the <span class="hlt">source</span> level and the ship speed and the <span class="hlt">source</span> level and the ship length. The alternate model proposed here represents the individual ship spectra by a modified rational spectrum where the poles and zeros are restricted to the real axis and the exponents of the terms are not restricted to integer values. An evaluation of this model on the <span class="hlt">source</span> spectra ensemble indicates that the rms errors are significantly less than those obtained with any model where the frequency dependence is represented by a single baseline spectrum. Furthermore, at high frequencies (400 to 1200 Hz), a single-term rational spectrum model is sufficient to describe the frequency dependence and, at the low frequencies (30 to 400 Hz), there is only a modest reduction in the rms error for a higher order model. Finally, a joint probability density on the two parameters of the single term model based on the measured histograms of these parameters is proposed. This probability density provides a mechanism for generating an ensemble of ship spectra. PMID:11931298</p> <div class="credits"> <p class="dwt_author">Wales, Stephen C; Heitmeyer, Richard M</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">314</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/21439348"> <span id="translatedtitle">Efficiency of neural transmission as a function of synaptic <span class="hlt">noise</span>, threshold, and <span class="hlt">source</span> characteristics.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">There has been a growing interest in the estimation of information carried by a single neuron and multiple single units or population of neurons to specific stimuli. In this paper we analyze, inspired by article of Levy and Baxter (2002), the efficiency of a neuronal communication by considering dendrosomatic summation as a Shannon-type channel (1948) and by considering such uncertain synaptic transmission as part of the dendrosomatic computation. Specifically, we study Mutual Information between input and output signals for different types of neuronal network architectures by applying efficient entropy estimators. We analyze the influence of the following quantities affecting transmission abilities of neurons: synaptic failure, activation threshold, firing rate and type of the input <span class="hlt">source</span>. We observed a number of surprising non-intuitive effects. It turns out that, especially for lower activation thresholds, significant synaptic <span class="hlt">noise</span> can lead even to twofold increase of the transmission efficiency. Moreover, the efficiency turns out to be a non-monotonic function of the activation threshold. We find a universal value of threshold for which a local maximum of Mutual Information is achieved for most of the neuronal architectures, regardless of the type of the <span class="hlt">source</span> (correlated and non-correlated). Additionally, to reach the global maximum the optimal firing rates must increase with the threshold. This effect is particularly visible for lower firing rates. For higher firing rates the influence of synaptic <span class="hlt">noise</span> on the transmission efficiency is more advantageous. <span class="hlt">Noise</span> is an inherent component of communication in biological systems, hence, based on our analysis, we conjecture that the neuronal architecture was adjusted to make more effective use of this attribute. PMID:21439348</p> <div class="credits"> <p class="dwt_author">Paprocki, Bartosz; Szczepanski, Janusz</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-03-23</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">315</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22053551"> <span id="translatedtitle">Cold-target recoil-ion momentum spectroscopy for diagnostics of high <span class="hlt">harmonics</span> of the extreme-ultraviolet free-electron laser light <span class="hlt">source</span> at SPring-8</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We have developed a cold-target recoil-ion momentum spectroscopy apparatus dedicated to the experiments using the extreme-ultraviolet light pulses at the free-electron laser facility, SPring-8 Compact SASE <span class="hlt">Source</span> test accelerator, in Japan and used it to measure spatial distributions of fundamental, second, and third <span class="hlt">harmonics</span> at the end station.</p> <div class="credits"> <p class="dwt_author">Liu, X.-J.; Fukuzawa, H.; Pruemper, G.; Ueda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); RIKEN, XFEL Project Head Office, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Okunishi, M.; Shimada, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Motomura, K.; Saito, N. [RIKEN, XFEL Project Head Office, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); National Metrology Institute of Japan, AIST, Tsukuba 305-8568 (Japan); Iwayama, H.; Nagaya, K.; Yao, M. [RIKEN, XFEL Project Head Office, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Rudenko, A. [RIKEN, XFEL Project Head Office, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Max Planck Advanced Study Group, CFEL, D-22607, Hamburg (Germany); Ullrich, J. [RIKEN, XFEL Project Head Office, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Max Planck Advanced Study Group, CFEL, D-22607, Hamburg (Germany); Max Planck-Insitut fuer Kernphysik, D-69117 Heidelberg (Germany); Foucar, L. [RIKEN, XFEL Project Head Office, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Institut fuer Kernphysik, Universitaet Frankfurt, D-60486 Frankfurt (Germany); Czasch, A.; Schmidt-Boecking, H.; Doerner, R. [Institut fuer Kernphysik, Universitaet Frankfurt, D-60486 Frankfurt (Germany); Nagasono, M.; Higashiya, A.; Yabashi, M. [RIKEN, XFEL Project Head Office, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); and others</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-05-15</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">316</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/20588835"> <span id="translatedtitle">Impact of various <span class="hlt">noises</span> on maximum reach in broadband light <span class="hlt">source</span> based high-capacity WDM passive optical networks.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We investigated the effects of various <span class="hlt">noises</span> on the performance of extended-reach WDM-PONs based on broadband light <span class="hlt">sources</span> (BLSs). The maximum reach in BLS based WDM-PONs was analyzed by taking into account the impact of relative intensity <span class="hlt">noise</span> of optical <span class="hlt">source</span>, chromatic dispersion of transmission fiber and in-band crosstalk. We confirmed that the system's performance of BLS based WDM-PONs would be strongly dependent on the equivalent optical bandwidth of optical <span class="hlt">source</span>. From the results, we found that the maximum reach in BLS based WDM-PONs operating at 1.25 Gb/s could be increased to be approximately 70 km of single-mode fiber as long as the chirp and relative intensity <span class="hlt">noise</span> (RIN) of optical <span class="hlt">source</span> would be suppressed properly. PMID:20588835</p> <div class="credits"> <p class="dwt_author">Kim, Chul Han</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-10</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">317</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27059266"> <span id="translatedtitle">Current <span class="hlt">Source</span> Topology for Wind Turbines With Decreased Mains Current <span class="hlt">Harmonics</span>, Further Reducible via Functional Minimization</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The paper presents a current-<span class="hlt">source</span> inverter topology tailored for large multi-megawatt wind turbines. The proposed topology can inherently benefit from the distance between the generator and the mains because the consequent length and possible layout of the power cables may enable the realization of a significant portion of the dc-link inductance. In order to improve the efficiency and to allow</p> <div class="credits"> <p class="dwt_author">Pierluigi Tenca; Andrew A. Rockhill; Thomas A. Lipo; Pietro Tricoli</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">318</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003JaJAP..42.2296N"> <span id="translatedtitle">Dominant <span class="hlt">Noise</span> <span class="hlt">Source</span> of Low-Frequency Fluctuation in AlGaAs/InGaAs High Electron Mobility Transistors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present an equivalent circuit model for the low-frequency <span class="hlt">noise</span> (LFN) in high electron mobility transistors (HEMTs). Our model correctly describes the dependence of LFN on gate voltage under low-drain-voltage conditions. Our model also allows us to investigate the location of the <span class="hlt">noise</span> <span class="hlt">sources</span> in HEMTs and leads to the fact that LFN arising from the extrinsic region is not negligible but dominant at a higher gate voltage.</p> <div class="credits"> <p class="dwt_author">Nishiyama, Shinya; Higuchi, Katsuhiko</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">319</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012PASA...29..251J"> <span id="translatedtitle">The Characterised <span class="hlt">Noise</span> HI <span class="hlt">Source</span> Finder: Detecting HI Galaxies Using a Novel Implementation of Matched Filtering</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The spectral line datacubes obtained from the Square Kilometre Array (SKA) and its precursors, such as the Australian SKA Pathfinder (ASKAP), will be sufficiently large to necessitate automated detection and parametrisation of <span class="hlt">sources</span>. Matched filtering is widely acknowledged as the best possible method for the automated detection of <span class="hlt">sources</span>. This paper presents the Characterised <span class="hlt">Noise</span> HI (CNHI) <span class="hlt">source</span> finder, which employs a novel implementation of matched filtering. This implementation is optimised for the 3-D nature of the HI spectral line observations of the planned Wide-field ASKAP Legacy L-band All-sky Blind surveY (WALLABY). The CNHI <span class="hlt">source</span> finder also employs a novel sparse representation of 3-D objects, with a high compression rate, to implement the Lutz one-pass algorithm on datacubes that are too large to process in a single pass. WALLABY will use ASKAP's phenomenal 30 square degree field of view to image ~70% of the sky. It is expected that WALLABY will find 500000 HI galaxies out to z~0.2.</p> <div class="credits"> <p class="dwt_author">Jurek, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">320</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24181207"> <span id="translatedtitle">Use of a large microphone array to identify <span class="hlt">noise</span> <span class="hlt">sources</span> during a rocket engine test firing and a rocket launch.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">A 70 microphone, 10 ft×10 ft, microphone phased array was built for use in the harsh environment of rocket launches. The array was setup at NASA Wallops launch pad 0A during a static test firing of Orbital Sciences' Antares engines, and again during the first launch of Antares vehicle. It was placed 400 ft away from the pad, and was hoisted on a scissor lift 40 ft above ground. The data sets provided unprecedented insights into rocket <span class="hlt">noise</span> <span class="hlt">sources</span>. The duct exit was found to be the primary <span class="hlt">source</span> during the static test firing; the large amount of water injected beneath the nozzle exit quenched all other <span class="hlt">sources</span>. The <span class="hlt">noise</span> maps during launch were found to be time-dependent. As the engines came to full power and became louder, the primary <span class="hlt">source</span> switched from the duct inlet to the duct exit. Further elevation of the vehicle caused spilling of the hot plume, resulting in a distributed <span class="hlt">noise</span> map covering most of the pad. As the entire plume emerged from the duct, and the on-deck water system came to full power, the plume itself became the loudest <span class="hlt">noise</span> <span class="hlt">source</span>. These <span class="hlt">noise</span> maps will help to improve the sound suppression system for future launches. PMID:24181207</p> <div class="credits"> <p class="dwt_author">Panda, Jayanta; Mosher, Robert N; Porter, Barry J</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_15");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' 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src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">321</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012PhRvL.109z3902L"> <span id="translatedtitle">Extreme Ultraviolet Interferometer Using High-Order <span class="hlt">Harmonic</span> Generation from Successive <span class="hlt">Sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present a new interferometer technique whereby multiple extreme ultraviolet light pulses are generated at different positions within a single laser focus (i.e., from successive <span class="hlt">sources</span>) with a highly controllable time delay. The interferometer technique is tested with two generating media to create two extreme ultraviolet light pulses with a time delay between them. The delay is found to be a consequence of the Gouy phase shift. Ultimately the apparatus is capable of accessing unprecedented time scales by allowing stable and repeatable delays as small as 100 zs.</p> <div class="credits"> <p class="dwt_author">Laban, D. E.; Palmer, A. J.; Wallace, W. C.; Gaffney, N. S.; Notermans, R. P. M. J. W.; Clevis, T. T. J.; Pullen, M. G.; Jiang, D.; Quiney, H. M.; Litvinyuk, I. V.; Kielpinski, D.; Sang, R. T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">322</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23368563"> <span id="translatedtitle">Extreme ultraviolet interferometer using high-order <span class="hlt">harmonic</span> generation from successive <span class="hlt">sources</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We present a new interferometer technique whereby multiple extreme ultraviolet light pulses are generated at different positions within a single laser focus (i.e., from successive <span class="hlt">sources</span>) with a highly controllable time delay. The interferometer technique is tested with two generating media to create two extreme ultraviolet light pulses with a time delay between them. The delay is found to be a consequence of the Gouy phase shift. Ultimately the apparatus is capable of accessing unprecedented time scales by allowing stable and repeatable delays as small as 100 zs. PMID:23368563</p> <div class="credits"> <p class="dwt_author">Laban, D E; Palmer, A J; Wallace, W C; Gaffney, N S; Notermans, R P M J W; Clevis, T T J; Pullen, M G; Jiang, D; Quiney, H M; Litvinyuk, I V; Kielpinski, D; Sang, R T</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-26</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">323</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA573319"> <span id="translatedtitle">Auditory Masking Patterns in Bottlenose Dolphins from Anthropogenic and Natural <span class="hlt">Noise</span> <span class="hlt">Sources</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The long-term goals of this project are to better understand and predict auditory masking in odontocetes with realistic, environmental <span class="hlt">noise</span> types. Current predictions based on Gaussian <span class="hlt">noise</span> masking will be improved upon. The objectives of this effort ar...</p> <div class="credits"> <p class="dwt_author">B. K. Branstetter</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">324</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50520258"> <span id="translatedtitle">A Predictable Robust Fully Programmable Analog Gaussian <span class="hlt">Noise</span> <span class="hlt">Source</span> for Mixed-Signal\\/Digital ATE</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A robust programmable analog Gaussian <span class="hlt">noise</span> generator suitable for mixed-signal\\/digital ATEs is presented. Unlike conventional methods (LFSR based <span class="hlt">noise</span> generators or resistor thermal <span class="hlt">noise</span> amplification techniques), the user has full control of the characteristics of the Gaussian signal. Indeed, the frequency band, the mean, and variance of the distribution are fully programmable over the voltage range within the supply rails.</p> <div class="credits"> <p class="dwt_author">Sadok Aouini; Gordon W. Roberts</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">325</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3735249"> <span id="translatedtitle">Adaptive <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">In biology, <span class="hlt">noise</span> implies error and disorder and is therefore something which organisms may seek to minimize and mitigate against. We argue that such <span class="hlt">noise</span> can be adaptive. Recent studies have shown that gene expression can be noisy, <span class="hlt">noise</span> can be genetically controlled, genes and gene networks vary in how noisy they are and <span class="hlt">noise</span> generates phenotypic differences among genetically identical cells. Such phenotypic differences can have fitness benefits, suggesting that evolution can shape <span class="hlt">noise</span> and that <span class="hlt">noise</span> may be adaptive. For example, gene networks can generate bistable states resulting in phenotypic diversity and switching among individual cells of a genotype, which may be a bet hedging strategy. Here, we review the <span class="hlt">sources</span> of <span class="hlt">noise</span> in gene expression, the extent to which <span class="hlt">noise</span> in biological systems may be adaptive and suggest that applying evolutionary rigour to the study of <span class="hlt">noise</span> is necessary to fully understand organismal phenotypes.</p> <div class="credits"> <p class="dwt_author">Viney, Mark; Reece, Sarah E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">326</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/20953510"> <span id="translatedtitle">Characterization of <span class="hlt">noise</span> <span class="hlt">sources</span> for two generations of computed radiography systems using powder and crystalline photostimulable phosphors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The performances of two generations of computed radiography (CR) were tested and compared in terms of resolution and <span class="hlt">noise</span> characteristics. The main aim was to characterize and quantify the <span class="hlt">noise</span> <span class="hlt">sources</span> in the images. The systems tested were (1) Agfa CR 25.0, a flying spot reader with powder phosphor image plates (MD 40.0); and (2) the Agfa DX-S, a line-scanning CR reader with needle crystal phosphor image plates (HD 5.0). For both systems, the standard metrics of presampled modulation transfer function (MTF), normalized <span class="hlt">noise</span> power spectra (NNPS) and detective quantum efficiency (DQE) were measured using standard radiation quality RQA5 as defined by the International Electrotechnical Commission. The various <span class="hlt">noise</span> <span class="hlt">sources</span> contributing to the NNPS were separated by using knowledge of their relationship with air kerma, MTF, absorption efficiency and antialiasing filters. The DX-S MTF was superior compared with the CR 25.0. The maximum difference in MTF between the DX-S scan and CR 25.0 subscan directions was 0.13 at 1.3 mm{sup -1}. For a nominal detector air kerma of 4 {mu}Gy, the peak DQE of the DX-S was 43({+-}3)%, which was over double that of the CR 25.0 of 18({+-}2)%. The additive electronic <span class="hlt">noise</span> was negligible on the CR 25.0 but calculated to be constant 3.4x10{sup -7} ({+-}0.4x10{sup -7}) mm{sup 2} at 3.9 {mu}Gy on the DX-S. The DX-S has improved image quality compared with a traditional flying spot reader. The separation of the <span class="hlt">noise</span> <span class="hlt">sources</span> indicates that the improvements in DQE of the DX-S are due not only to the higher quantum, efficiency and MTF, but also the lower structure, secondary quantum, and excess <span class="hlt">noise</span>.</p> <div class="credits"> <p class="dwt_author">Mackenzie, Alistair; Honey, Ian D. [KCARE, King's College Hospital, Denmark Hill, London, SE5 9RS (United Kingdom)</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-08-15</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">327</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/17879798"> <span id="translatedtitle">Characterization of <span class="hlt">noise</span> <span class="hlt">sources</span> for two generations of computed radiography systems using powder and crystalline photostimulable phosphors.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The performances of two generations of computed radiography (CR) were tested and compared in terms of resolution and <span class="hlt">noise</span> characteristics. The main aim was to characterize and quantify the <span class="hlt">noise</span> <span class="hlt">sources</span> in the images. The systems tested were (1) Agfa CR 25.0, a flying spot reader with powder phosphor image plates (MD 40.0); and (2) the Agfa DX-S, a line-scanning CR reader with needle crystal phosphor image plates (HD 5.0). For both systems, the standard metrics of presampled modulation transfer function (MTF), normalized <span class="hlt">noise</span> power spectra (NNPS) and detective quantum efficiency (DQE) were measured using standard radiation quality RQA5 as defined by the International Electrotechnical Commission. The various <span class="hlt">noise</span> <span class="hlt">sources</span> contributing to the NNPS were separated by using knowledge of their relationship with air kerma, MTF, absorption efficiency and antialiasing filters. The DX-S MTF was superior compared with the CR 25.0. The maximum difference in MTF between the DX-S scan and CR 25.0 subscan directions was 0.13 at 1.3 mm(-1). For a nominal detector air kerma of 4 microGy, the peak DQE of the DX-S was 43 (+/-3)%, which was over double that of the CR 25.0 of 18 (+/-2)%. The additive electronic <span class="hlt">noise</span> was negligible on the CR 25.0 but calculated to be constant 3.4 x 10(-7) (+/-0.4 x 10(-7)) mm2 at 3.9 microGy on the DX-S. The DX-S has improved image quality compared with a traditional flying spot reader. The separation of the <span class="hlt">noise</span> <span class="hlt">sources</span> indicates that the improvements in DQE of the DX-S are due not only to the higher quantum, efficiency and MTF, but also the lower structure, secondary quantum, and excess <span class="hlt">noise</span>. PMID:17879798</p> <div class="credits"> <p class="dwt_author">Mackenzie, Alistair; Honey, Ian D</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">328</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18648029"> <span id="translatedtitle">A theoretical study of helicopter rotor <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A comprehensive theoretical study of the problem of helicopter rotor <span class="hlt">noise</span> radiation is presented. The theory includes blade slap, rotation <span class="hlt">noise</span> and vortex <span class="hlt">noise</span> effects. Peak spectral levels over the ``vortex <span class="hlt">noise</span>'' region are shown to be due to the higher <span class="hlt">harmonics</span> of the rotational <span class="hlt">noise</span>. An exact theoretical expression for the <span class="hlt">noise</span> radiation has been used as the basis</p> <div class="credits"> <p class="dwt_author">M. V. Lowson; J. B. Ollerhead</p> <p class="dwt_publisher"></p> <p class="publishDate">1969-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">329</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6558683"> <span id="translatedtitle">Investigation of possible <span class="hlt">sources</span> of 1/f <span class="hlt">noise</span> in irradiated n-channel power MOSFETs</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">1/f <span class="hlt">noise</span> in irradiated n-channel power MOSFETs is compared to interface- and oxide-trapped charge densities. The <span class="hlt">noise</span> follows the bias dependences predicted by an equation based on the number fluctuation model derived for <span class="hlt">noise</span> in the saturation region. The magnitude of the <span class="hlt">noise</span> switched between two distinct levels when the bias was reversed during post-irradiation annealing. The <span class="hlt">noise</span> did not correlate well with interface traps or oxide trapped charge. Border traps provide a reasonable explanation, with charge compensation being an important effect. During positive-bias annealing, near-interfacial traps are compensated and no longer contribute to the 1/f <span class="hlt">noise</span>. However, when the bias is reversed, the traps are decompensated and the <span class="hlt">noise</span> increases again.</p> <div class="credits"> <p class="dwt_author">Ploor, M.D.; Schrimpf, R.D.; Galloway, K.F. (Univ. of Arizona, Tucson, AZ (United States). Dept. of Electrical and Computer Engineering)</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">330</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EPJWC..4104017O"> <span id="translatedtitle">Surface Carrier Dynamics on Semiconductor Studied with Femtosecond Core-Level Photoelectron Spectroscopy Using Extreme Ultraviolet High-Order <span class="hlt">Harmonic</span> <span class="hlt">Source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We have used a femtosecond time-resolved core-level surface PES system based on the 92-eV <span class="hlt">harmonic</span> <span class="hlt">source</span> to study the surface carrier dynamics that induces the transient SPV on semiconductor surfaces. We clarified the temporal evolution of the transient SPV characterized by the time of the photo-generated carrier separation and recombination. This result demonstrates the potential of this technique for clarifying the initial stage of the surface carrier dynamics after photoexcitation.</p> <div class="credits"> <p class="dwt_author">Oguri, K.; Tsunoi, T.; Kato, K.; Nakano, H.; Nishikawa, T.; Gotoh, H.; Tateno, K.; Sogawa, T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">331</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56244639"> <span id="translatedtitle">1 pm spectrally narrowed ArF excimer laser injection locked by fourth <span class="hlt">harmonic</span> seed <span class="hlt">source</span> of 773.6 nm Ti:sapphire laser</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We have achieved spectrum narrowing to 1 pm in a high-power ArF excimer laser injection locked by an all solid-state fourth <span class="hlt">harmonic</span> (193.4 nm) seed <span class="hlt">source</span> of 773.6 nm Ti:sapphire laser radiation. Superior laser properties such as sufficient output energy (90 mJ\\/pulse, 50 pps), locking efficiency exceeding 90%, wavelength drift less than 0.4 pm, and spectrum bandwidth fluctuation less than</p> <div class="credits"> <p class="dwt_author">T. Kasamatsu; M. Tsunekane; H. Sekita; Y. Morishige; S. Kishida</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">332</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60102588"> <span id="translatedtitle">Investigation of hydrothermal boiling and steam quenching as possible <span class="hlt">sources</span> of volcanic tremor and geothermal ground <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Volcanic tremor and geothermal ground <span class="hlt">noise</span> are sustained seismic emissions associated with volcanic and geothermal activity. In this study I investigate whether such signals could be caused by boiling or steam quenching in liquid-dominated zones of subterranean hydrothermal systems. The framework for the study is a conceptual model that assumes: (1) the fundamental <span class="hlt">source</span> of seismic energy is the growth\\/collapse</p> <div class="credits"> <p class="dwt_author">Leet</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">333</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1982efnr.rept.....D"> <span id="translatedtitle">Effects of flight on <span class="hlt">noise</span> radiated from convected ring <span class="hlt">sources</span> in coaxial dual flow. Part 2: The <span class="hlt">noise</span> from heated jets</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The effects of flight on <span class="hlt">noise</span> from heated jets are discussed. The effects of the additionally, extraneously-generated dipole and simple <span class="hlt">source</span> terms which arise as a result of the density gradients across the fluid interfaces were incorporated. The coaxial flows with inverted profiles are shown to be quieter than the conventional profiles; however, the benefit of <span class="hlt">noise</span> reduction at higher outer-to-inner area ratios is totally offset as the inverted profile incurs a significant massloss and thrust-loss. Amongst all the possible coaxial configurations when on of the coaxial streams is heated-conventional profile (CP), inverted profile (IP) and the variable stream control engine (VSCE) cycle-and at constant massflow and thrust, a VSCE-cycle is the most desirable and the best possible engine cycle inasmuch as it provides over more than 18.0 dB reduction in SPL (as compared against <span class="hlt">noise</span> from a CP-cycle) at all angles, both statically and in flight, for area ratios Sigma 0.25.</p> <div class="credits"> <p class="dwt_author">Dash, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">334</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51988561"> <span id="translatedtitle">Low-<span class="hlt">noise</span> preamplifier with input and feedback transformers for low <span class="hlt">source</span> resistance sensors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We describe the design, schematics, and performances of a very-low-<span class="hlt">noise</span>, low-frequency preamplifier. It operates in the 5 Hz–100 kHz range and offers an input equivalent voltage <span class="hlt">noise</span> density as low as 65 pV\\/&sqrt;Hz; the current <span class="hlt">noise</span> increases with frequency and settles to about 1.5 pA\\/&sqrt;Hz at 100 kHz. The amplifier uses input and feedback signal transformers and operates in full</p> <div class="credits"> <p class="dwt_author">J. Lepaisant; M. Lam Chok Sing; D. Bloyet</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">335</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27077273"> <span id="translatedtitle">A New Circuit Topology for the Realization of Very Low <span class="hlt">Noise</span>, High Stability Voltage <span class="hlt">Sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A new topology for the realization of high-stability very low <span class="hlt">noise</span> voltage references is presented. The topology relies on a self-biasing circuit configuration based on a low-<span class="hlt">noise</span> operational amplifier (OA). The series connection of a number of forward-biased low-<span class="hlt">noise</span> diodes is used as an internal reference for generating any desired output voltage. The circuit may include a temperature stabilization system</p> <div class="credits"> <p class="dwt_author">Carmine Ciofi; Graziella Scandurra; Gianluca Cannata</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">336</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60484957"> <span id="translatedtitle">Analysis and ranking of the acoustic disturbance potential of petroleum-industry activities and other <span class="hlt">sources</span> of <span class="hlt">noise</span> in the environment of marine mammals in Alaska. Final report</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The study compares the relative magnitudes and effects on marine mammals of <span class="hlt">noise</span> from oil and gas industry activities with <span class="hlt">noise</span> from other <span class="hlt">sources</span> in Alaska OCS and coastal waters. The study procedure incorporates the receiver, <span class="hlt">source</span> and path concepts generally used in acoustic analysis. The receiver characterization includes a review of marine mammal distribution in Alaska and a map</p> <div class="credits"> <p class="dwt_author">C. I. Malme; P. R. Miles; G. S. Miller; W. J. Richardson; D. G. Roseneau</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">337</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ktb.engin.umich.edu/RSG/pubs_files/IGARSS-2006_Lim_and_Ruf_CNCS.pdf"> <span id="translatedtitle">Calibration of a Fully Polarimetric Microwave Radiometer Using a Digital Polarimeric <span class="hlt">Noise</span> <span class="hlt">Source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Correlated <span class="hlt">Noise</span> Calibration Standard (CNCS) is an electronic device that generates two channels of broadband microwave <span class="hlt">noise</span> with a programmable degree of complex correlation. It can supply signals to the input of a microwave radiometer with independently variable vertical, horizontal, 3rd and 4th Stokes brightness temperatures. An X-Band version of the CNCS has been evaluated with the NASA Goddard</p> <div class="credits"> <p class="dwt_author">Boon H Lim; Christopher S Ruf</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">338</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://198.246.98.21/niosh/mining/pubs/pdfs/aoampa.pdf"> <span id="translatedtitle">Application of a microphone phased array to identify <span class="hlt">noise</span> <span class="hlt">sources</span> on a horizontal vibrating screen</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In coal preparation plants, workers are often exposed to sound levels exceeding 90 dB(A). Vibrating screens are viewed as a significant contributor to preparation plant <span class="hlt">noise</span>. Reducing the sound levels generated by vibrating screens could reduce the <span class="hlt">noise</span> exposures of preparation plant employees. The National Institu te for Occupational Safety and Health (NIOSH) measured the sound power level generated by</p> <div class="credits"> <p class="dwt_author">David S. Yantek; Hugo E. Camargo; Rudy J. Matetic</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">339</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1514574"> <span id="translatedtitle"><span class="hlt">Noise</span> properties and phase resolution of interferometer systems interrogated by narrowband fiber ASE <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We present the results of a detailed theoretical and experimental study of the <span class="hlt">noise</span> properties of various interferometer systems interrogated using narrowband spontaneous emission. The filtering effect of the interferometer is shown to introduce periodic structure in the optical <span class="hlt">noise</span> spectrum with a period, level, and modulation depth that depends on the exact interferometer configuration and implementation, as well as</p> <div class="credits"> <p class="dwt_author">Hyo Sang Kim; Ronald P. H. Haaksman; Trevor P. Newson; David J. Richardson</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">340</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/15119621"> <span id="translatedtitle">Detailed study of an efficient blue laser <span class="hlt">source</span> by second-<span class="hlt">harmonic</span> generation in a semimonolithic cavity for the cooling of strontium atoms.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We have constructed a blue laser <span class="hlt">source</span> consisting of an amplified, grating tuned diode laser that is frequency doubled by a KNbO3 crystal in a compact standing wave cavity and produces as much as 200 mW of internal second-<span class="hlt">harmonic</span> power. We have analyzed the unusual characteristics of this standing wave cavity to clarify the advantages and disadvantages of this configuration as an alternative to a ring cavity for second-<span class="hlt">harmonic</span> generation. We emphasize its efficiency and stability and the fact that it has an inherent walk-off compensation, similar to twin crystal configurations. We demonstrate its utility for laser cooling and trapping of earth alkalis by stabilizing the laser to the 461-nm transition of strontium, using a heat pipe, and then forming a magneto-optic trap of strontium from a Zeeman-slowed atomic beam. PMID:15119621</p> <div class="credits"> <p class="dwt_author">Klappauf, Bruce G; Bidel, Yannick; Wilkowski, David; Chanelière, Thierry; Kaiser, Robin</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-04-20</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a 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class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a style="font-weight: bold;">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_19");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">341</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3269440"> <span id="translatedtitle">Relative impact of key <span class="hlt">sources</span> of systematic <span class="hlt">noise</span> in Affymetrix and Illumina gene-expression microarray experiments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Background Systematic processing <span class="hlt">noise</span>, which includes batch effects, is very common in microarray experiments but is often ignored despite its potential to confound or compromise experimental results. Compromised results are most likely when re-analysing or integrating datasets from public repositories due to the different conditions under which each dataset is generated. To better understand the relative <span class="hlt">noise</span>-contributions of various factors in experimental-design, we assessed several Illumina and Affymetrix datasets for technical variation between replicate hybridisations of Universal Human Reference (UHRR) and individual or pooled breast-tumour RNA. Results A varying degree of systematic <span class="hlt">noise</span> was observed in each of the datasets, however in all cases the relative amount of variation between standard control RNA replicates was found to be greatest at earlier points in the sample-preparation workflow. For example, 40.6% of the total variation in reported expressions were attributed to replicate extractions, compared to 13.9% due to amplification/labelling and 10.8% between replicate hybridisations. Deliberate probe-wise batch-correction methods were effective in reducing the magnitude of this variation, although the level of improvement was dependent on the <span class="hlt">sources</span> of <span class="hlt">noise</span> included in the model. Systematic <span class="hlt">noise</span> introduced at the chip, run, and experiment levels of a combined Illumina dataset were found to be highly dependant upon the experimental design. Both UHRR and pools of RNA, which were derived from the samples of interest, modelled technical variation well although the pools were significantly better correlated (4% average improvement) and better emulated the effects of systematic <span class="hlt">noise</span>, over all probes, than the UHRRs. The effect of this <span class="hlt">noise</span> was not uniform over all probes, with low GC-content probes found to be more vulnerable to batch variation than probes with a higher GC-content. Conclusions The magnitude of systematic processing <span class="hlt">noise</span> in a microarray experiment is variable across probes and experiments, however it is generally the case that procedures earlier in the sample-preparation workflow are liable to introduce the most <span class="hlt">noise</span>. Careful experimental design is important to protect against <span class="hlt">noise</span>, detailed meta-data should always be provided, and diagnostic procedures should be routinely performed prior to downstream analyses for the detection of bias in microarray studies.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">342</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27059500"> <span id="translatedtitle">Single-Phase Voltage <span class="hlt">Source</span> Inverter With a Bidirectional Buck–Boost Stage for <span class="hlt">Harmonic</span> Injection and Distributed Generation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A transformerless single-phase inverter topology is proposed that can operate over a wide dc input voltage range and has the ability to track reference signals with fast dynamics, making it suitable for <span class="hlt">harmonic</span> elimination and distributed generation applications. The necessary capacitor and inductor are easier to design than those for filtering the output of traditional inverters. Unlike traditional inverters, no</p> <div class="credits"> <p class="dwt_author">Ahmed Mohamed Salamah; Stephen J. Finney; Barry W. Williams</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">343</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/19111398"> <span id="translatedtitle">High- and low-frequency <span class="hlt">noise</span> in Cs and in liquid metal ion <span class="hlt">sources</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Fundamental Physics space missions set rigid thrust <span class="hlt">noise</span> limits for liquid metal ion thrusters used as actuators on drag-free platforms aboard the spacecraft. We have measured current-, voltage- and thrust <span class="hlt">noise</span> of Cs and In LMIS, foreseen as prime candidates in these missions. In the high-frequency range, quasiperiodic oscillations around approximately 10(5)Hz can be observed for both types of emitters with frequency depending on emission current. In the low-frequency range (1-10(-3)Hz), which is particularly important for drag-free control, different types of <span class="hlt">noise</span> events are observed, which in some instances show definite signs of deterministic chaos (period doubling, self-similarity). High-frequency current oscillations are generally ascribed to electro-hydrodynamic oscillations of the TAYLOR cone and the jet at its apex, with concomitant emission of charged nanodroplets. Comparison of theory and experiment shows unsatisfactory agreement in predicted vs. measured current oscillation frequencies and large disagreement in droplet emission frequencies. No theory is presently available for describing low-frequency <span class="hlt">noise</span> events. In terms of a linearized Mair theory it is, however, shown that these <span class="hlt">noise</span> events can be efficiently described by spontaneous variations in electrical emitter impedance. In spite of this impedance <span class="hlt">noise</span>, the mission requirements for thrust <span class="hlt">noise</span> (<0.1microN/Hz(1/2)) can be met by a thrust-stabilized In emitter. PMID:19111398</p> <div class="credits"> <p class="dwt_author">Rüdenauer, F; Mitterauer, J; Genovese, A</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-11-21</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">344</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005ASAJ..118.1844H"> <span id="translatedtitle"><span class="hlt">Noise</span> modeling, <span class="hlt">noise</span> experiment, and <span class="hlt">noise</span> inversion</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Recent developments in inverting ambient <span class="hlt">noise</span> to obtain bottom reflection properties originated from an understanding of <span class="hlt">noise</span> behavior and from <span class="hlt">noise</span> modeling. Sea-surface <span class="hlt">noise</span> can be modeled equivalently as a ray, wave, or mode phenomenon, but often the ray or flux approach provides the most insight (explaining, e.g., the <span class="hlt">noise</span>-notch or low-frequency <span class="hlt">noise</span> enhancement). Theoretically, <span class="hlt">noise</span> vertical directionality is surprisingly sensitive to the effective depth of the sheet of sound <span class="hlt">sources</span>, and this is borne out in the spread of behaviors found experimentally. A number of <span class="hlt">noise</span> inversion approaches have been proposed based on coherence or directionality of sea-surface <span class="hlt">noise</span>, individual ships or shipping, and airplane doppler. Using a drifting vertical array as a means to measure directionality, one can infer reflection coefficient versus angle and frequency. One can then use this directly for propagation calculation, or alternatively invert to geoacoustic parameters with the help of a fast <span class="hlt">noise</span> model. A further development is to recover the reflection phase using spectral factorization, then Fourier transform to get the impulse response, which becomes a sub-bottom profile for a drifting array. At 4-kHz design frequency, the layer structure thus determined compares well with a boomer down to 15 m.</p> <div class="credits"> <p class="dwt_author">Harrison, Chris H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">345</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..1512286J"> <span id="translatedtitle">Applying the seismic interferometry method to vertical seismic profile data using tunnel excavation <span class="hlt">noise</span> as <span class="hlt">source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the frame of the research conducted to develop efficient strategies for investigation of rock properties and fluids ahead of tunnel excavations the seismic interferometry method was applied to analyze the data acquired in boreholes instrumented with geophone strings. The results obtained confirmed that seismic interferometry provided an improved resolution of petrophysical properties to identify heterogeneities and geological structures ahead of the excavation. These features are beyond the resolution of other conventional geophysical methods but can be the cause severe problems in the excavation of tunnels. Geophone strings were used to record different types of seismic <span class="hlt">noise</span> generated at the tunnel head during excavation with a tunnelling machine and also during the placement of the rings covering the tunnel excavation. In this study we show how tunnel construction activities have been characterized as <span class="hlt">source</span> of seismic signal and used in our research as the seismic <span class="hlt">source</span> signal for generating a 3D reflection seismic survey. The data was recorded in vertical water filled borehole with a borehole seismic string at a distance of 60 m from the tunnel trace. A reference pilot signal was obtained from seismograms acquired close the tunnel face excavation in order to obtain best signal-to-<span class="hlt">noise</span> ratio to be used in the interferometry processing (Poletto et al., 2010). The seismic interferometry method (Claerbout 1968) was successfully applied to image the subsurface geological structure using the seismic wave field generated by tunneling (tunnelling machine and construction activities) recorded with geophone strings. This technique was applied simulating virtual shot records related to the number of receivers in the borehole with the seismic transmitted events, and processing the data as a reflection seismic survey. The pseudo reflective wave field was obtained by cross-correlation of the transmitted wave data. We applied the relationship between the transmission response and the reflection response for a 1D multilayer structure, and next 3D approach (Wapenaar 2004). As a result of this seismic interferometry experiment the 3D reflectivity model (frequencies and resolution ranges) was obtained. We proved also that the seismic interferometry approach can be applied in asynchronous seismic auscultation. The reflections detected in the virtual seismic sections are in agreement with the geological features encountered during the excavation of the tunnel and also with the petrophysical properties and parameters measured in previous geophysical borehole logging. References Claerbout J.F., 1968. Synthesis of a layered medium from its acoustic transmision response. Geophysics, 33, 264-269 Flavio Poletto, Piero Corubolo and Paolo Comeli.2010. Drill-bit seismic interferometry whith and whitout pilot signals. Geophysical Prospecting, 2010, 58, 257-265. Wapenaar, K., J. Thorbecke, and D. Draganov, 2004, Relations between reflection and transmission responses of three-dimensional inhomogeneous media: Geophysical Journal International, 156, 179-194.</p> <div class="credits"> <p class="dwt_author">Jurado, Maria Jose; Teixido, Teresa; Martin, Elena; Segarra, Miguel; Segura, Carlos</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">346</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2001ASAJ..115.2622H"> <span id="translatedtitle">The effect of rail <span class="hlt">sources</span> on <span class="hlt">noise</span>-sensitive construction in Chicago</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Because of Chicago's dominance as a rail center in the 19th and 20th centuries and the miles of track present, parcels of land available for residential and other <span class="hlt">noise</span>-sensitive construction frequently lie adjacent to freight, commuter, and Chicago Transit Authority (CTA) tracks. As A-weighted sound levels commonly exceed 105 dBA underneath CTA elevated tracks, special methods of <span class="hlt">noise</span> abatement for high-rise and other construction to address high <span class="hlt">noise</span> levels are necessary. Also discussed will be methods of establishing acoustical criteria appropriate for commercial and residential interior spaces.</p> <div class="credits"> <p class="dwt_author">Homans, Brian L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">347</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.fda.gov/biologicsbloodvaccines/internationalactivities/ucm271079.htm"> <span id="translatedtitle">Regulatory <span class="hlt">Harmonization</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://google2.fda.gov/search?client=FDAgov&site=FDAgov&lr=&proxystylesheet=FDAgov&output=xml_no_dtd&&proxycustom=%3CADVANCED/%3E">Center for Biologics Evaluation and Research (CBER)</a></p> <p class="result-summary">. The Agency engages in a range of explicit <span class="hlt">harmonization</span> initiatives, a subset of which includes the participation of CBER. ... More results from www.fda.gov/biologicsbloodvaccines/internationalactivities</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">348</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA249793"> <span id="translatedtitle">Modification of 95 GHz Radar <span class="hlt">Source</span> Module for Low Phase <span class="hlt">Noise</span> Operation.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This report describes the results of a modification to the University of Massachusetts 95 GHz polarimetric radar. This modification was done to reduce problems caused by phase <span class="hlt">noise</span> originating from the radar's millimeter-wave oscillator.</p> <div class="credits"> <p class="dwt_author">R. E. McIntosh</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">349</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013PhPl...20i2702G"> <span id="translatedtitle"><span class="hlt">Noise</span> <span class="hlt">sources</span> and competition between stimulated Brillouin and Raman scattering: A one-dimensional steady-state approach</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A 1D steady-state model is developed to deal with stimulated scattering processes. The volume and boundary <span class="hlt">noise</span> <span class="hlt">sources</span> for scattered light are discussed in detail. Our results indicate that the boundary <span class="hlt">noise</span> <span class="hlt">sources</span> may play a significant role in estimating the reflectivity of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). With the capability of our model to deal with broadband scattered light, we find that pump depletion could be the main reason to the anti-correlation between SBS and SRS versus electron density observed in experiments. A simple method is proposed to phenomenologically include the effect of nonlinear saturation mechanisms in our model and reasonable results are obtained.</p> <div class="credits"> <p class="dwt_author">Gong, Tao; Li, Zhichao; Zhao, Bin; Hu, Guang-yue; Zheng, Jian</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">350</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50967412"> <span id="translatedtitle"><span class="hlt">Sources</span> of non-physiologic <span class="hlt">noise</span> in simultaneous EEG-fMRI data: A phantom study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Simultaneous EEG-fMRI studies require an understanding of the <span class="hlt">noise</span> characteristics of the acquisition environment so that appropriate pre-processing steps may be taken to remove known artifacts from the data stream. Using a phantom approach, we have developed a general methodology for characterizing non-physiologic <span class="hlt">noise</span> in EEG signal and demonstrate the use of this methodology for a specific MR scanner and</p> <div class="credits"> <p class="dwt_author">David Politte; F. Prior; C. Ponton; T. Nolan; L. Larson-Prior</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">351</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/6082717"> <span id="translatedtitle">High-resolution DOA estimation based on independent <span class="hlt">noise</span> component for correlated signal <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this article, a modified complex-valued FastICA algorithm is utilized to extract the specific feature of the Gaussian <span class="hlt">noise</span>\\u000a component from mixtures so that the estimated component is as independent as possible to the other non-Gaussian signal components.\\u000a Once the <span class="hlt">noise</span> basis vector is obtained, we can estimate direction of arrival by searching the array manifold for direction\\u000a vectors, which</p> <div class="credits"> <p class="dwt_author">Shiaw-wu Chen; Chih-wei Jen; Ann-chen Chang</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">352</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/35888387"> <span id="translatedtitle">High and low-frequency <span class="hlt">noise</span> in Cs and in liquid metal ion <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Fundamental Physics space missions set rigid thrust <span class="hlt">noise</span> limits for liquid metal ion thrusters used as actuators on drag-free platforms aboard the spacecraft. We have measured current-, voltage- and thrust <span class="hlt">noise</span> of Cs and In LMIS, foreseen as prime candidates in these missions. In the high-frequency range, quasiperiodic oscillations around ?105Hz can be observed for both types of emitters with</p> <div class="credits"> <p class="dwt_author">F. Rüdenauer; J. Mitterauer; A. Genovese</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">353</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010APhy...56..198Z"> <span id="translatedtitle">The use of receiving arrays for measuring underwater <span class="hlt">noise</span> levels of moving <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A method of measuring underwater <span class="hlt">noise</span> levels of moving ships with the use of a vertical receiving array is considered. An algorithm is proposed for synthesizing the weight vector that provides a given measurement accuracy with maximal <span class="hlt">noise</span> suppression for the cases of an interference with a known structure and an a priori unknown interference (the adaptive synthesis). Results of both numerical simulation of the method and its experimental testing under actual sea conditions are presented.</p> <div class="credits"> <p class="dwt_author">Zakonov, Yu. I.; Korotin, P. I.; Orlov, D. A.; Sazonov, S. P.; Slizhov, A. B.; Turchin, V. I.; Fiks, G. E.; Fiks, I. Sh.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">354</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51514242"> <span id="translatedtitle">The effect of rail <span class="hlt">sources</span> on <span class="hlt">noise</span>-sensitive construction in Chicago</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Because of Chicago's dominance as a rail center in the 19th and 20th centuries and the miles of track present, parcels of land available for residential and other <span class="hlt">noise</span>-sensitive construction frequently lie adjacent to freight, commuter, and Chicago Transit Authority (CTA) tracks. As A-weighted sound levels commonly exceed 105 dBA underneath CTA elevated tracks, special methods of <span class="hlt">noise</span> abatement for</p> <div class="credits"> <p class="dwt_author">Brian L. Homans</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">355</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://dsnra.jpl.nasa.gov/development/MM_wave/ALMA_memo311.pdf"> <span id="translatedtitle"><span class="hlt">Noise</span> Measurements of YIG-Tuned Oscillator <span class="hlt">Sources</span> for the ALMA LO</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In this memo, we present measurements of the <span class="hlt">noise</span> of YIG-tuned oscillators (YTOs) at their fundamental frequency and multiplied to millimeter-wave frequencies. Based on these measurements, we verify that the phase <span class="hlt">noise</span> goals for this component can be met with a 300-kHz bandwidth phase lock loop (PLL) as long as the fundamental YTO frequency is not above 27 GHz. We</p> <div class="credits"> <p class="dwt_author">Eric W. Bryerton; Dorsey L. Thacker; Kamaljeet S. Saini; Richard F. Bradley</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">356</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2000AIPC..509..513H"> <span id="translatedtitle">A novel crack reconstruction method for steam generator tube ECT with <span class="hlt">noise</span> <span class="hlt">sources</span> outside</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In eddy current testing of steam generator tubes, the signals obtained are always <span class="hlt">noised</span> by many factors because of the complex environment. Some of these <span class="hlt">noise</span> factors are caused by the support plates, the expansion part of the tube and the tube sheets outside. Previous works show that the <span class="hlt">noises</span> of support plates can be reduced by a multi-frequency method. However, the elimination of <span class="hlt">noises</span> from the expansion part of the tube is proved impossible using the multi-frequency method only. A new signal processing method is introduced in this paper by applying a differential filter using the two dimensions scan data. Signal <span class="hlt">noise</span> ratio (SNR) is increased significantly, even a small signal from outer defects can be recognized. Furthermore, a new method for the crack reconstruction from these <span class="hlt">noised</span> signals has been developed with a fast signal prediction and the conjugate gradient algorithm considering the outside ferromagnetic structures such as support plates and tube sheets. The electromotive force signals used here for the crack reconstruction are laboratory data obtained by a newly developed four-sensor probe with mutual induction and differential outputs. Shapes of artificial cracks are reconstructed satisfactorily in short CPU time. .</p> <div class="credits"> <p class="dwt_author">Huang, Haoyu; Takagi, Toshiyuki; Fukutomi, Hiroyuki</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">357</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27573083"> <span id="translatedtitle">Measurement of Vertical Distribution of Truck <span class="hlt">Noise</span> <span class="hlt">Sources</span> During Highway Cruise Pass-Bys by Acoustic Beam Forming</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A measurement program was completed to determine the vertical distribution of heavy-truck <span class="hlt">noise</span> <span class="hlt">sources</span> for pass-by events on an in-service highway for vehicles operating under cruise conditions. In addition to data on heavy trucks, some data were obtained for medium trucks and light-duty vehicles. The measurements were performed with acoustic beam forming, which provided visualization of the sound radiation of</p> <div class="credits"> <p class="dwt_author">Paul R. Donavan; Bruce Rymer</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">358</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/6079936"> <span id="translatedtitle">Absolute subcriticality measurement without calibration and detection efficiency dependence by the /sup 252/Cf <span class="hlt">source</span>-driven <span class="hlt">noise</span> method</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The /sup 252/Cf-<span class="hlt">source</span>-driven <span class="hlt">noise</span> analysis method determines the subcriticality of a system containing fissionable material from the ratio of cross power spectral densities between the detectors that detect particles from the fission process and between these detectors and an ionization chamber containing a spontaneously fissioning neutron <span class="hlt">source</span> which provides neutrons to induce fission in the system. This method has two advantages: (1) a calibration is not required and thus subcriticality can be determined from measurements only on the subcritical system of interest, and (2) the subcriticality is independent of the type of detector or its efficiency. These properties of this technique are illustrated by measurements.</p> <div class="credits"> <p class="dwt_author">Mihalczo, J.T.; King, W.T.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">359</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70014779"> <span id="translatedtitle">Resonance of a fluid-driven crack: radiation properties and implications for the <span class="hlt">source</span> of long-period events and <span class="hlt">harmonic</span> tremor.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">A dynamic <span class="hlt">source</span> model is presented, in which a 3-D crack containing a viscous compressible fluid is excited into resonance by an impulsive pressure transient applied over a small area DELTA S of the crack surface. The crack excitation depends critically on two dimensionless parameters called the crack stiffness and viscous damping loss. According to the model, the long-period event and <span class="hlt">harmonic</span> tremor share the same <span class="hlt">source</span> but differ in the boundary conditions for fluid flow and in the triggering mechanism setting up the resonance of the <span class="hlt">source</span>, the former being viewed as the impulse response of the tremor generating system and the later representing the excitation due to more complex forcing functions.-from Author</p> <div class="credits"> <p class="dwt_author">Chouet, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">360</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1996AIPC..370.1029B"> <span id="translatedtitle"><span class="hlt">Noise</span> measurements in shunted, shorted, and fully electroded quartz gauges in the saturn plasma radiation <span class="hlt">source</span> x-ray simulator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This paper describes recent work to improve the measurement of the stress response of materials to intense, short pulses of radiation. When Saturn fires, large prompt electrical <span class="hlt">noise</span> pulses are induced in stress measurement circuits. The conventional wisdom has been that the shorted guard ring quartz gauge was the only configuration with acceptable prompt signal-to-<span class="hlt">noise</span> characteristics for stress measurements in this pulsed radiation environment. However, because of abnormal signal distortion, the shorted guard ring gauge is restricted to a maximum stress of about 8 kbars. Below this level, the normal, quantified signal distortion is correctable with analytical deconvolution techniques. The shunted guard ring gauge is acceptable for high fidelity measurements to about 25 kbars with negligible signal distortion. Experiments were conducted on the Saturn soft x-ray <span class="hlt">source</span> which show that higher fidelity shunted guard ring gauges can successfully measure stress with acceptable induced <span class="hlt">noise</span>. We also found that a 50-ohm impedance matching resistor at the gauge reduced the prompt <span class="hlt">noise</span> amplitude and improved the baseline quality of the measurement prior to shock wave arrival.</p> <div class="credits"> <p class="dwt_author">Barrett, W. H.; Greenwoll, J. I.; Smith, C. W.; Johnson, D. E.; de La Cruz, C. F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-05-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">361</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/776581"> <span id="translatedtitle">Simultaneous ballistic deficit immunity and resilience to parallel <span class="hlt">noise</span> <span class="hlt">sources</span>: A new pulse shaping technique</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A new and different time variant pulse processing system has been developed based on a simple CR-RC filter and two analog switches. The new pulse processing technique combines both ballistic deficit immunity and resilience to parallel <span class="hlt">noise</span> without a significant compromise to the low energy resolution, generally considered a mutually exclusive requirement. The filter is realized by combining two different pulse-shaping techniques. One of the techniques creates a low rate of curvature at the pulse peak, which reduces ballistic deficit, while the second technique increases the tolerance to low frequency <span class="hlt">noise</span> by modifying the <span class="hlt">noise</span> history. Several experimental measurements are presented, including tests on a co-planar grid CdZnTe detector. Improvements on both the resolution and line shape are shown for the 662 keV line of 137Cs.</p> <div class="credits"> <p class="dwt_author">Fabris, Lorenzo; Becker, John A.; Goulding, Frederick S.; Madden, Norman W.</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-10-11</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">362</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52986431"> <span id="translatedtitle">Incoherence, Quantum Fluctuations, and <span class="hlt">Noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">An examination is made of the relationship between the uncertainty principle and minimum amplifier <span class="hlt">noise</span>. First, the concept of coherence is discussed, and an incoherence parameter is defined in terms of the uncertainty that enters into the uncertainty principle. <span class="hlt">Harmonic</span> oscillator states are examined for coherence. The concept of <span class="hlt">noise</span> is then discussed and contrasted with incoherence, <span class="hlt">noise</span> referring to</p> <div class="credits"> <p class="dwt_author">I. R. Senitzky</p> <p class="dwt_publisher"></p> <p class="publishDate">1962-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">363</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2809934"> <span id="translatedtitle">Benefits of Localization and Speech Perception with Multiple <span class="hlt">Noise</span> <span class="hlt">Sources</span> in Listeners with a Short-electrode Cochlear Implant</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Background Research suggests that for individuals with significant low-frequency hearing, implantation of a short-electrode cochlear implant may provide benefits of improved speech perception abilities. Because this strategy combines acoustic and electrical hearing within the same ear while at the same time preserving low-frequency residual acoustic hearing in both ears, localization abilities may also be improved. However, very little research has focused on the localization and spatial hearing abilities of users with a short-electrode cochlear implant. Purpose The purpose of this study was to evaluate localization abilities for listeners with a short-electrode cochlear implant who continue to wear hearing aids in both ears. A secondary purpose was to document speech perception abilities using a speech in <span class="hlt">noise</span> test with spatially-separate <span class="hlt">noise</span> <span class="hlt">sources</span>. Research Design Eleven subjects that utilized a short-electrode cochlear implant and bilateral hearing aids were tested on localization and speech perception with multiple <span class="hlt">noise</span> locations using an eight-loudspeaker array. Performance was assessed across four listening conditions using various combinations of cochlear implant and/or hearing aid use. Results Results for localization showed no significant difference between using bilateral hearing aids and bilateral hearing aids plus the cochlear implant. However, there was a significant difference between the bilateral hearing aid condition and the implant plus use of a contralateral hearing aid for all eleven subjects. Results for speech perception showed a significant benefit when using bilateral hearing aids plus the cochlear implant over use of the implant plus only one hearing aid. Conclusion Combined use of both hearing aids and the cochlear implant show significant benefits for both localization and speech perception in <span class="hlt">noise</span> for users with a short-electrode cochlear implant. These results emphasize the importance of low-frequency information in two ears for the purpose of localization and speech perception in <span class="hlt">noise</span>.</p> <div class="credits"> <p class="dwt_author">Dunn, Camille C.; Perreau, Ann; Gantz, Bruce; Tyler, Richard</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">364</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011RScI...82f3114W"> <span id="translatedtitle">Femtosecond time-resolved photoelectron spectroscopy with a vacuum-ultraviolet photon <span class="hlt">source</span> based on laser high-order <span class="hlt">harmonic</span> generation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A laser-based tabletop approach to femtosecond time-resolved photoelectron spectroscopy with photons in the vacuum-ultraviolet (VUV) energy range is described. The femtosecond VUV pulses are produced by high-order <span class="hlt">harmonic</span> generation (HHG) of an amplified femtosecond Ti:sapphire laser system. Two generations of the same setup and results from photoelectron spectroscopy in the gas phase are discussed. In both generations, a toroidal grating monochromator was used to select one <span class="hlt">harmonic</span> in the photon energy range of 20-30 eV. The first generation of the setup was used to perform photoelectron spectroscopy in the gas phase to determine the bandwidth of the <span class="hlt">source</span>. We find that our HHG <span class="hlt">source</span> has a bandwidth of 140 +/- 40 meV. The second and current generation is optimized for femtosecond pump-probe photoelectron spectroscopy with high flux and a small spot size at the sample of the femtosecond probe pulses. The VUV radiation is focused into the interaction region with a toroidal mirror to a spot smaller than 100 × 100 ?m2 and the flux amounts to 1010 photons/s at the sample at a repetition rate of 1 kHz. The duration of the monochromatized VUV pulses is determined to be 120 fs resulting in an overall pump-probe time resolution of 135 +/- 5 fs. We show how this setup can be used to map the transient valence electronic structure in molecular dissociation.</p> <div class="credits"> <p class="dwt_author">Wernet, Philippe; Gaudin, Jérôme; Godehusen, Kai; Schwarzkopf, Olaf; Eberhardt, Wolfgang</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">365</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/21721681"> <span id="translatedtitle">Femtosecond time-resolved photoelectron spectroscopy with a vacuum-ultraviolet photon <span class="hlt">source</span> based on laser high-order <span class="hlt">harmonic</span> generation.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">A laser-based tabletop approach to femtosecond time-resolved photoelectron spectroscopy with photons in the vacuum-ultraviolet (VUV) energy range is described. The femtosecond VUV pulses are produced by high-order <span class="hlt">harmonic</span> generation (HHG) of an amplified femtosecond Ti:sapphire laser system. Two generations of the same setup and results from photoelectron spectroscopy in the gas phase are discussed. In both generations, a toroidal grating monochromator was used to select one <span class="hlt">harmonic</span> in the photon energy range of 20-30 eV. The first generation of the setup was used to perform photoelectron spectroscopy in the gas phase to determine the bandwidth of the <span class="hlt">source</span>. We find that our HHG <span class="hlt">source</span> has a bandwidth of 140 ± 40 meV. The second and current generation is optimized for femtosecond pump-probe photoelectron spectroscopy with high flux and a small spot size at the sample of the femtosecond probe pulses. The VUV radiation is focused into the interaction region with a toroidal mirror to a spot smaller than 100 × 100 ?m(2) and the flux amounts to 10(10) photons/s at the sample at a repetition rate of 1 kHz. The duration of the monochromatized VUV pulses is determined to be 120 fs resulting in an overall pump-probe time resolution of 135 ± 5 fs. We show how this setup can be used to map the transient valence electronic structure in molecular dissociation. PMID:21721681</p> <div class="credits"> <p class="dwt_author">Wernet, Philippe; Gaudin, Jérôme; Godehusen, Kai; Schwarzkopf, Olaf; Eberhardt, Wolfgang</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">366</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012JaJAP..51fFB09N"> <span id="translatedtitle">Development of Coherent Extreme-Ultraviolet Scatterometry Microscope with High-Order <span class="hlt">Harmonic</span> Generation <span class="hlt">Source</span> for Extreme-Ultraviolet Mask Inspection and Metrology</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In extreme-ultraviolet (EUV) lithography, defect-free mask production is one of the critical issues for the high-volume manufacturing of semiconductor devices. We developed a coherent EUV scatterometry microscope (CSM), which is a simple lensless system. The CSM records diffraction from mask patterns with a charge-coupled-device (CCD) camera directly, which is illuminated with a coherent EUV light. Since a practical standalone system is required by the industry, we developed a standalone CSM system employing a high-order <span class="hlt">harmonic</span> generation (HHG) EUV <span class="hlt">source</span>. The 59th high-order <span class="hlt">harmonic</span> generation of 13.5 nm wavelength is pumped by a tabletop, 6 mJ, 32 fs, Ti:sapphire laser system. The EUV output energy of 1 ?W is successfully achieved. We performed the observation of an EUV mask using the HHG-CSM system. The detection limit of the line defect size is improved to 2 nm for the high output power of the HHG EUV <span class="hlt">source</span>.</p> <div class="credits"> <p class="dwt_author">Nakasuji, Masato; Tokimasa, Akifumi; Harada, Tetsuo; Nagata, Yutaka; Watanabe, Takeo; Midorikawa, Katsumi; Kinoshita, Hiroo</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">367</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22062347"> <span id="translatedtitle">Femtosecond time-resolved photoelectron spectroscopy with a vacuum-ultraviolet photon <span class="hlt">source</span> based on laser high-order <span class="hlt">harmonic</span> generation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A laser-based tabletop approach to femtosecond time-resolved photoelectron spectroscopy with photons in the vacuum-ultraviolet (VUV) energy range is described. The femtosecond VUV pulses are produced by high-order <span class="hlt">harmonic</span> generation (HHG) of an amplified femtosecond Ti:sapphire laser system. Two generations of the same setup and results from photoelectron spectroscopy in the gas phase are discussed. In both generations, a toroidal grating monochromator was used to select one <span class="hlt">harmonic</span> in the photon energy range of 20-30 eV. The first generation of the setup was used to perform photoelectron spectroscopy in the gas phase to determine the bandwidth of the <span class="hlt">source</span>. We find that our HHG <span class="hlt">source</span> has a bandwidth of 140 {+-} 40 meV. The second and current generation is optimized for femtosecond pump-probe photoelectron spectroscopy with high flux and a small spot size at the sample of the femtosecond probe pulses. The VUV radiation is focused into the interaction region with a toroidal mirror to a spot smaller than 100 x 100 {mu}m{sup 2} and the flux amounts to 10{sup 10} photons/s at the sample at a repetition rate of 1 kHz. The duration of the monochromatized VUV pulses is determined to be 120 fs resulting in an overall pump-probe time resolution of 135 {+-} 5 fs. We show how this setup can be used to map the transient valence electronic structure in molecular dissociation.</p> <div class="credits"> <p class="dwt_author">Wernet, Philippe; Gaudin, Jerome; Godehusen, Kai; Schwarzkopf, Olaf; Eberhardt, Wolfgang [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin (Germany)</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-06-15</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">368</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA410071"> <span id="translatedtitle">Realistic Versus the Spherical Head Model in EEG Dipole <span class="hlt">Source</span> Analysis in the Presence of <span class="hlt">Noise</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The performance of the three-shell spherical head model versus the performance of the realistic head model is investigated when solving the inverse problem with a single dipole, in the presence of <span class="hlt">noise</span>. This is evaluated by inspecting the average dipole ...</p> <div class="credits"> <p class="dwt_author">B. Vanrumste G. Van Hoey R. Van de Walle P. Van Hese M. D'Have</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">369</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18607974"> <span id="translatedtitle">A study of methods of characterising the effects of internal <span class="hlt">noise</span> <span class="hlt">sources</span> on submarine flank arrays</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Passive sonar arrays are used on submarines and surface vessels to detect the presence and position of other ships in the vicinity and locate and identify potential targets. <span class="hlt">Noise</span> generated by the machinery inside the submarine carrying the array can affect the capacity to detect other vessels. The aim of this work was to develop methods of characterising the effects</p> <div class="credits"> <p class="dwt_author">Y. Gargouri; V. Nautet; P. R. Wagstaff; C. Giangreco</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">370</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52421168"> <span id="translatedtitle"><span class="hlt">Sources</span> and Transfer Mechanisms of <span class="hlt">Noise</span> in horizontal Seismometers evaluated by FE-Modelling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Barometric pressure induced <span class="hlt">noise</span> in seismometer records is one of the major limiting factors in analyzing these data. Esp. the horizontal components are strongly affected. Aims of a joint research project by the Geodynamic Observatory Moxa and the Black Forest Observatory are to point out the main physical transfer mechanisms and to develop reliable reduction methods. The barometric pressure influence</p> <div class="credits"> <p class="dwt_author">C. Kroner</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">371</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.bape.gouv.qc.ca/sections/mandats/sismiques/documents/dd5.pdf"> <span id="translatedtitle"><span class="hlt">NOISE</span> <span class="hlt">SOURCES</span> IN THE SEA AND THE IMPACT FOR THOSE WHO LIVE THERE</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In recent years the volume and spatial extent of anthropological <span class="hlt">noise</span> pollution of the oceans has become clearer as underwater acoustic research has matured in the open literature following the run-down of the cold war. In parallel, the range, depth and dependence of marine mammals on sound for communication and environmental sensing has been brought sharply into focus by an</p> <div class="credits"> <p class="dwt_author">JOHN POTTER; ERIC DELORY</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">372</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=PB2000108256"> <span id="translatedtitle">NIST Measurement Services: Measurement Assurance Program for the Spectral Density of Relative Intensity <span class="hlt">Noise</span> of Optical Fiber <span class="hlt">Sources</span> Near 1550 nm.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This paper provides the documentation to establish a measurement assurance program (MAP) for the spectral density of relative intensity <span class="hlt">noise</span> (RIN) of optical <span class="hlt">sources</span>. A standard is made available to industry for high-precision calibration of RIN measurem...</p> <div class="credits"> <p class="dwt_author">G. E. Obarski J. D. Splett</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">373</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N8714120"> <span id="translatedtitle">Effects of Background <span class="hlt">Noise</span> on Total <span class="hlt">Noise</span> Annoyance.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">Two experiments were conducted to assess the effects of combined community <span class="hlt">noise</span> <span class="hlt">sources</span> on annoyance. The first experiment baseline relationships between annoyance and <span class="hlt">noise</span> level for three community <span class="hlt">noise</span> <span class="hlt">sources</span> (jet aircraft flyovers, traffic and air ...</p> <div class="credits"> <p class="dwt_author">K. F. Willshire</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">374</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008PhDT........54V"> <span id="translatedtitle">On the characterization of <span class="hlt">noise</span> <span class="hlt">sources</span> in supersonic shock containing jets</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Research on the <span class="hlt">noise</span> produced by military aircraft has seen a renewed interest due to the increasing concerns of communities around airbases and airports. Radiated <span class="hlt">noise</span> associated with high-speed military style engines is the main contributor of the overall <span class="hlt">noise</span> produced by modern aircraft, especially in military applications where the jets typically are at very high velocity and temperature, and have low bypass ratios. The acoustic and aerodynamic properties of high-speed jets are investigated experimentally in this thesis. Measurements are conducted in the Penn State high speed jet <span class="hlt">noise</span> facility, after the validation of the newly upgraded rig. Axisymmetric Nozzles are investigated as well as nozzles with a military style shape. The database of flow measurements in supersonic shock containing jets is very scarce. This research focuses on performing flow measurements in shock containing jets in an effort to obtain valuable parameters for the modeling of the <span class="hlt">noise</span> propagated by such flows. Mean flow measurements of the jets are performed with pitot probes traversing the flow. These measurements are used as a qualification tool for a CFD simulation of the flow field with good overall agreement. Measurements in supersonic rectangular jets also uncover the presence of axes switching in fully, over- and under-expanded cases, with the location of this axes switch being further downstream in the fully expanded case. Acoustic data are gathered in shock containing screeching jets. Different techniques are investigated in order to provide some reduction of the screech tones. Optical Deflectometry measurements are performed in shock containing jets and show that the screech tones have no effect on the properties of the convecting structures. On the other hand, the strength of the shock present in the flow seems to have an effect on the convection velocity. Finally, the simultaneous correlation between the flow field fluctuations and the acoustic far field is measured. This suggests that the OD sensors can be used for localizing the <span class="hlt">noise</span> generation in the jet. Preliminary results of this kind show that the highest frequencies are generated close to the exit plane of the nozzle.</p> <div class="credits"> <p class="dwt_author">Veltin, Jeremy</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">375</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1989CRASM.308..703F"> <span id="translatedtitle">Prediction of potential <span class="hlt">noise</span> interactions in axial-flow machines - Application to the helicopter fenestron</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A method for predicting the far-field <span class="hlt">noise</span> created in a rotor by the flow around cylindrical obstacles (such as support arms) placed downstream of the rotor is proposed. Application of the method to helicopter rotor blades shows that this <span class="hlt">noise</span> <span class="hlt">source</span> can account for the fundamental and first <span class="hlt">harmonics</span> of the blade frequencies. It is suggested that higher frequences may be due to the absorption of atmospheric turbulence.</p> <div class="credits"> <p class="dwt_author">Fournier, Francette; Roger, Michel</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">376</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21428793"> <span id="translatedtitle">Multi-<span class="hlt">Harmonic</span> Cavities for Increasing RF Breakdown Threshold</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A multi-<span class="hlt">harmonic</span> asymmetric cavity is predicted to sustain higher acceleration gradients than a conventional pillbox cavity, 55% higher in one example, when driven by external RF <span class="hlt">harmonic</span> <span class="hlt">sources</span>. Simulations of multi-<span class="hlt">harmonic</span> excitation in such a cavity are described, either by a charged drive beam or by external RF <span class="hlt">sources</span>. An accelerator structure based on multi-<span class="hlt">harmonic</span> cavity is proposed.</p> <div class="credits"> <p class="dwt_author">Jiang, Y. [Beam Physics Laboratory, Yale University, 272 Whitney Ave., New Haven, CT 06511 (United States); Kazakov, S. Yu. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kuzikov, S. V. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Institute of Applied Physics, Nizhny Novgorod (Russian Federation); Hirshfield, J. L. [Beam Physics Laboratory, Yale University, 272 Whitney Ave., New Haven, CT 06511 (United States); Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-11-04</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">377</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://origin.cdc.gov/niosh/mining/pubs/pdfs/aoamp.pdf"> <span id="translatedtitle">Application of a microphone phased array to identify <span class="hlt">noise</span> <span class="hlt">sources</span> on a roof bolting machine</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Exposure to excessive <span class="hlt">noise</span> over time can cause permanent hearing loss. Workers in the mining industry are frequently exposed to A-weighted sound levels in excess of 90 dB. The A-weighted sound level at the roof bolter operator's location can exceed 100 dB while drilling. The National Institute for Occupational Safety and Health (NIOSH) measured the sound pressure at the roof</p> <div class="credits"> <p class="dwt_author">David S. Yantek; J. Shawn Peterson; Adam K. Smith</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">378</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/19840834"> <span id="translatedtitle">Transmission characteristics of cyclotron <span class="hlt">harmonic</span> waves in plasma</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In recent years the importance of cyclotron <span class="hlt">harmonic</span> waves has become apparent in many branches of plasma physics. For example, it has been demonstrated that they are involved in the anomalously high <span class="hlt">noise</span> radiation near the electron cyclotron <span class="hlt">harmonic</span> frequencies that has been observed from thermonuclear fusion study devices, and that they can explain the cyclotron <span class="hlt">harmonic</span> resonances observed in</p> <div class="credits"> <p class="dwt_author">F. W. Crawford; H. H. Weiss</p> <p class="dwt_publisher"></p> <p class="publishDate">1966-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">379</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5752454"> <span id="translatedtitle">Subcriticality measurements for two coupled uranyl nitrate solution tanks using /sup 252/Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis methods</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The subcriticality of two interacting solution tanks was determined using /sup 252/Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis methods. This work was supported by a program of collaboration between the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan to study aspects of nuclear criticality safety related to the development of fast breeder technology. These experiments were the first test of this method for an interacting system with materials (in this case, uranyl nitrate 140 g U/l, 93.15 wt% /sup 235/U) typical of nuclear materials in processing plants.</p> <div class="credits"> <p class="dwt_author">Mihalczo, J.T.; Blakeman, E.D.; King, W.T.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">380</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60064657"> <span id="translatedtitle">Subcriticality of two uranyl nitrate flat cylindrical tanks spaced in air by [sup 252]Cf-<span class="hlt">source</span>-driven <span class="hlt">noise</span> analysis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The subcritical neutron multiplication factors k for two parallel, axially separated, flat cylindrical tanks separated up to 57.91cm in air and containing enriched uranyl (93.1 wt% [sup 235]U) nitrate solution (71.6-cm-i.d. tanks, 8.91-cm solution thickness, 1.555 g\\/cm[sup 3] solution density, and 404g U\\/l uranium density) were measured by the [sup 252]Cf-<span class="hlt">source</span>-driven <span class="hlt">noise</span> analysis method with measured k values varying from</p> <div class="credits"> <p class="dwt_author">J. T. Mihalczo; E. D. Blakeman; V. K. Pare; T. E. Valentine; D. J. Auslander</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_18");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">381</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55908168"> <span id="translatedtitle">Low-<span class="hlt">noise</span> computer-controlled current <span class="hlt">source</span> for quantum coherence experiments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We describe a dual current <span class="hlt">source</span> designed to provide static flux biases for a superconducting qubit and for the Superconducting QUantum Interference Device (SQUID) which measures the qubit state. The <span class="hlt">source</span> combines digitally programmable potentiometers with a stabilized voltage <span class="hlt">source</span>. Each channel has a maximum output of +\\/-1 mA, and can be adjusted with an accuracy of about +\\/-1 nA.</p> <div class="credits"> <p class="dwt_author">S. Linzen; T. L. Robertson; T. Hime; B. L. T. Plourde; P. A. Reichardt; John Clarke</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">382</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/969251"> <span id="translatedtitle">Feasibility Study for a Seeded Hard X-ray <span class="hlt">Source</span> Based on a Two-Stage Echo-Enabled <span class="hlt">Harmonic</span> Generation FEL</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We propose and analyze a scheme to achieve a seeded hard x-ray <span class="hlt">source</span> based on a two-stage echo-enabled <span class="hlt">harmonic</span> generation (EEHG) FEL. In the scheme an 180 nm seed laser covering the whole bunch is first used to modulate the beam when beam energy is 2 GeV. After passing through a strong chicane complicated fine structures are introduced into the phase space. The beam is again modulated by a short 180 nm laser that only interacts with the rear part of the beam and accelerated to 6 GeV. A chicane is then used to convert the energy modulation imparted to the rear part of the beam into density modulation. The density-modulated beam is sent through a radiator to generate intense 6 nm radiation which will be used to interact with the front fresh part of the bunch. Finally we generate in the front part of the beam density modulation at the 1199th <span class="hlt">harmonic</span> of the seed laser. We will discuss the issues related to the realization of the seeded hard x-ray FEL.</p> <div class="credits"> <p class="dwt_author">Xiang, Dao; Huang, Z.; Ratner, D.; Stupakov, G.; /SLAC</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-11</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">383</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27057259"> <span id="translatedtitle">UPFC modeling in the <span class="hlt">harmonic</span> domain</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper outlines the extension of <span class="hlt">harmonic</span> domain modeling to flexible ac transmission system (FACTS) devices which contain series voltage injection elements. The proposed iterative technique is capable of modeling generic combinations of series and shunt converters; representing these elements as <span class="hlt">harmonic</span> current and voltage <span class="hlt">sources</span>, respectively. The <span class="hlt">harmonic</span> performance of these converter combinations is characterized in terms of dc</p> <div class="credits"> <p class="dwt_author">Christopher Collins; N. Watson; A. Wood</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">384</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007JGRB..112.7413A"> <span id="translatedtitle">Assessment of <span class="hlt">noise</span> in GPS coordinate time series: Methodology and results</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We propose a methodology to assess the <span class="hlt">noise</span> characteristics in time series of position estimates for permanent Global Positioning System (GPS) stations. Least squares variance component estimation (LS-VCE) is adopted to cope with any type of <span class="hlt">noise</span> in the data. LS-VCE inherently provides the precision of (co)variance estimators. One can also apply statistical hypothesis testing in conjunction with LS-VCE. Using the w-test statistic, a combination of white <span class="hlt">noise</span> and flicker <span class="hlt">noise</span> turns out in general to best characterize the <span class="hlt">noise</span> in all three position components. An interpretation for the colored <span class="hlt">noise</span> of the series is given. Unmodelled periodic effects in the data will be captured by a set of <span class="hlt">harmonic</span> functions for which we rely on the least squares <span class="hlt">harmonic</span> estimation (LS-HE) method and parameter significance testing developed in the same framework as LS-VCE. Having included <span class="hlt">harmonic</span> functions into the model, practically only white <span class="hlt">noise</span> can be shown to remain in the data. Remaining time correlation, present only at very high frequencies (spanning a few days only), is expressed as a first-order autoregressive <span class="hlt">noise</span> process. It can be caused by common and well-known <span class="hlt">sources</span> of errors like atmospheric effects as well as satellite orbit errors. The autoregressive <span class="hlt">noise</span> should be included in the stochastic model to avoid the overestimation (upward bias) of power law <span class="hlt">noise</span>. The results confirm the presence of annual and semiannual signals in the series. We observed also significant periodic patterns with periods of 350 days and its fractions 350/n, n = 2, …, 8 that resemble the repeat time of the GPS constellation. Neglecting these <span class="hlt">harmonic</span> signals in the functional model can seriously overestimate the rate uncertainty.</p> <div class="credits"> <p class="dwt_author">Amiri-Simkooei, A. R.; Tiberius, C. C. J. M.; Teunissen, P. J. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">385</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/332101873206h656.pdf"> <span id="translatedtitle">Effects of dipole position, orientation and <span class="hlt">noise</span> on the accuracy of EEG <span class="hlt">source</span> localization</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Background  The electroencephalogram (EEG) reflects the electrical activity in the brain on the surface of scalp. A major challenge in\\u000a this field is the localization of <span class="hlt">sources</span> in the brain responsible for eliciting the EEG signal measured at the scalp. In\\u000a order to estimate the location of these <span class="hlt">sources</span>, one must correctly model the <span class="hlt">sources</span>, i.e., dipoles, as well as the</p> <div class="credits"> <p class="dwt_author">Kevin Whittingstall; Gerhard Stroink; Larry Gates; JF Connolly; Allen Finley</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">386</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1522415"> <span id="translatedtitle">Low phase <span class="hlt">noise</span> millimeter-wave frequency <span class="hlt">sources</span> using InP-based HBT MMIC technology</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A family of millimeter-wave <span class="hlt">sources</span> based on InP heterojunction bipolar transistor (HBT) monolithic microwave\\/millimeter-wave integrated circuit (MMIC) technology has been developed. These <span class="hlt">sources</span> include 40-GHz, 46-GHz, 62-GHz MMIC fundamental mode oscillators, and a 95-GHz frequency <span class="hlt">source</span> module using a 23.8-GHz InP HBT MMIC dielectric resonator oscillator (DRO) in conjunction with a GaAs-based high electron mobility transistor (HEMT) MMIC frequency quadrupler</p> <div class="credits"> <p class="dwt_author">Huei Wang; Kwo Wei Chang; Liem T. Tran; John C. Cowles; Thomas R. Block; Eric W. Lin; G. Samuel Dow; Aaron K. Oki; Dwight C. Streit; Barry R. Allen</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">387</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/10179438"> <span id="translatedtitle"><span class="hlt">Harmonic</span> generation at high intensities</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Atomic electrons subject to intense laser fields can absorb many photons, leading either to multiphoton ionization or the emission of a single, energetic photon which can be a high multiple of the laser frequency. The latter process, high-order <span class="hlt">harmonic</span> generation, has been observed experimentally using a range of laser wavelengths and intensities over the past several years. <span class="hlt">Harmonic</span> generation spectra have a generic form: a steep decline for the low order <span class="hlt">harmonics</span>, followed by a plateau extending to high <span class="hlt">harmonic</span> order, and finally an abrupt cutoff beyond which no <span class="hlt">harmonics</span> are discernible. During the plateau the <span class="hlt">harmonic</span> production is a very weak function of the process order. <span class="hlt">Harmonic</span> generation is a promising <span class="hlt">source</span> of coherent, tunable radiation in the XUV to soft X-ray range which could have a variety of scientific and possibly technological applications. Its conversion from an interesting multiphoton phenomenon to a useful laboratory radiation <span class="hlt">source</span> requires a complete understanding of both its microscopic and macroscopic aspects. We present some recent results on the response of single atoms at intensities relevant to the short pulse experiments. The calculations employ time-dependent methods, which we briefly review in the next section. Following that we discuss the behavior of the <span class="hlt">harmonics</span> as a function of laser intensity. Two features are notable: the slow scaling of the <span class="hlt">harmonic</span> intensities with laser intensity, and the rapid variation in the phase of the individual <span class="hlt">harmonics</span> with respect to <span class="hlt">harmonic</span> order. We then give a simple empirical formula that predicts the extent of the plateau for a given ionization potential, wavelength and intensity.</p> <div class="credits"> <p class="dwt_author">Schafer, K.J.; Krause, J.L.; Kulander, K.C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">388</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009PhRvE..80f1914A"> <span id="translatedtitle">Spontaneous brain activity as a <span class="hlt">source</span> of ideal 1/f <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We study the electroencephalogram (EEG) of 30 closed-eye awake subjects with a technique of analysis recently proposed to detect punctual events signaling rapid transitions between different metastable states. After single-EEG-channel event detection, we study global properties of events simultaneously occurring among two or more electrodes termed coincidences. We convert the coincidences into a diffusion process with three distinct rules that can yield the same ? only in the case where the coincidences are driven by a renewal process. We establish that the time interval between two consecutive renewal events driving the coincidences has a waiting-time distribution with inverse power-law index ??2 corresponding to ideal 1/f <span class="hlt">noise</span>. We argue that this discovery, shared by all subjects of our study, supports the conviction that 1/f <span class="hlt">noise</span> is an optimal communication channel for complex networks as in art or language and may therefore be the channel through which the brain influences complex processes and is influenced by them.</p> <div class="credits"> <p class="dwt_author">Allegrini, Paolo; Menicucci, Danilo; Bedini, Remo; Fronzoni, Leone; Gemignani, Angelo; Grigolini, Paolo; West, Bruce J.; Paradisi, Paolo</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">389</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18662147"> <span id="translatedtitle">A modified Ibrahim time domain algorithm for operational modal analysis including <span class="hlt">harmonic</span> excitation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Operational modal analysis procedures are efficient techniques to identify modal properties of structures excited through unknown random <span class="hlt">noise</span> produced during operation. In many practical cases, <span class="hlt">harmonic</span> excitations are often present in addition to the white-<span class="hlt">noise</span> and, if the <span class="hlt">harmonic</span> frequency is close to structural frequencies, standard identification techniques fail. Here, a method is presented to take into account the <span class="hlt">harmonic</span></p> <div class="credits"> <p class="dwt_author">P. Mohanty; D. J. Rixen</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">390</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18876107"> <span id="translatedtitle">GENERAL: Stability Analysis of an Inverted Pendulum Subjected to Combined High Frequency <span class="hlt">Harmonics</span> and Stochastic Excitations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Stability of vertical upright position of an inverted pendulum with its suspension point subjected to high frequency <span class="hlt">harmonics</span> and stochastic excitations is investigated. Two classes of excitations, i.e., combined high frequency <span class="hlt">harmonic</span> excitation and Gaussian white <span class="hlt">noise</span> excitation, and high frequency bounded <span class="hlt">noise</span> excitation, respectively, are considered. Firstly, the terms of high frequency <span class="hlt">harmonic</span> excitations in the equation of motion</p> <div class="credits"> <p class="dwt_author">Zhi-Long Huang; Xiao-Ling Jin; Zi-Qi Zhu</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">391</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26672530"> <span id="translatedtitle">Blind <span class="hlt">source</span> separation of ship-radiated <span class="hlt">noise</span> based on generalized Gaussian model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">When the distribution of the <span class="hlt">sources</span> cannot be estimated accurately, the ICA algorithms failed to separate the mixtures blindly. The generalized Gaussian model (GGM) is presented in ICA algorithm since it can model non-Gaussian statistical structure of different <span class="hlt">source</span> signals easily. By inferring only one parameter, a wide class of statistical distributions can be characterized. By using maximum likelihood (ML)</p> <div class="credits"> <p class="dwt_author">Wei Kong; Bin Yang</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">392</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFM.S23A2214B"> <span id="translatedtitle">Combining Three Component Beamforming and Wave Hindcast Model Data to Investigate <span class="hlt">Source</span> Regions of Ambient Seismic <span class="hlt">Noise</span>: a New Zealand Case Study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Recent studies employing ambient seismic <span class="hlt">noise</span> as an energy <span class="hlt">source</span> have extended our knowledge of crustal and upper mantle structures and of time-variable geological processes. It has further been demonstrated that the combination of earthquake and ambient seismic <span class="hlt">noise</span> signals can potentially overcome restrictions inherent to traditional event-based seismology alone. However, uncertainties in the <span class="hlt">source</span> location and <span class="hlt">source</span> mechanism of ambient seismic <span class="hlt">noise</span> constitute a major obstacle in fully utilizing the results of seismic <span class="hlt">noise</span> investigations. Several authors have addressed this problem but focused on the <span class="hlt">source</span> regions of vertical-component <span class="hlt">noise</span> recordings only. In this study, we conduct plane-wave beamforming using vertical- and horizontal-component seismic <span class="hlt">noise</span> recordings from a dense deployment of 61 broadband instruments on New Zealand's western North Island to investigate the <span class="hlt">source</span> regions and <span class="hlt">source</span> mechanisms of both Rayleigh and Love waves contained in the ambient seismic <span class="hlt">noise</span> wavefield. We compare beamformer observations with locations of potential <span class="hlt">sources</span> inferred from bathymetry and an ocean wave hindcast model of the New Zealand region employing the theoretical framework for microseism excitation of Longuet-Higgins (Phil. Trans. R. Soc. Lon., 1950] and Bromirski and Duennebier (J. Geophys. Res., 2002). Our results indicate that the <span class="hlt">source</span> regions of both the primary and secondary microseisms are mostly located close to New Zealand's coastline and few significant deep water <span class="hlt">sources</span> can be identified. The strongest <span class="hlt">source</span> region appears to be the south-western tip of New Zealand's South Island where large ocean swells coincide with a narrow continental shelf. This observation is underlined by the good correlation between near-coastal ocean significant wave height and seismic significant wave height. However, quantification of this relationship in terms of Longuet-Higgins' [1950] theory requires a more detailed treatment of coastal effects on ocean waves than is currently common in wave hindcast models. We also observe that Rayleigh and Love waves are generated in similar areas but with differing intensities. When averaged over several months, our beamformer results for vertical- and horizontal-component <span class="hlt">noise</span> recordings show broadly similar and homogeneous azimuthal distributions. This is an important result for ongoing studies focused on estimating Green's functions from ambient <span class="hlt">noise</span> cross correlations in New Zealand.</p> <div class="credits"> <p class="dwt_author">Behr, Y.; Townend, J.; Bowen, M. M.; Carter, L.; Gorman, R. M.; Bannister, S. C.; Brooks, L. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">393</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/786174"> <span id="translatedtitle">Measurement and Analysis of Conducted <span class="hlt">Noise</span> at Main Control Room in Uljin NPP</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Electromagnetic measurements were performed at the power ports of the Plant Control System (PCS) and the Core Protection Calculator (CPC) in Uljin to obtain the conducted <span class="hlt">noise</span> level, which can be utilized to determine the electromagnetic environment test limit for the equipment qualification test, for equipment to be installed in the NPP. The measurements indicated that the maximum <span class="hlt">noise</span> of the continuous conducted <span class="hlt">noise</span> at the low-frequency range of from 30 Hz to 50kHz at the PCS was higher than that at the CPC. It was found that the low-frequency conducted <span class="hlt">noise</span> consists of a 60-Hz power <span class="hlt">source</span> frequency and its even and odd <span class="hlt">harmonic</span> frequencies. The odd <span class="hlt">harmonic</span> was more predominant than the even.</p> <div class="credits"> <p class="dwt_author">Goo, Cheol-Soo; Kim, Bok-Ryul; Cho, Won-Seo</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-06-17</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">394</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N7327935"> <span id="translatedtitle"><span class="hlt">Noise</span> and <span class="hlt">Noise</span> Sickness.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">Basic concepts and questions about <span class="hlt">noise</span>, which contribute to a proper understanding of the characteristic of industrial <span class="hlt">noise</span> as well as an experimental acoustical complex for the study of the <span class="hlt">noise</span> factor, are examined. Special attention has been given ...</p> <div class="credits"> <p class="dwt_author">Y. T. Andreyevagalanina S. V. Alekeseyev A. V. Kadyskin G. A. Suvopov</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">395</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5982020"> <span id="translatedtitle">Subcriticality of two uranyl nitrate flat cylindrical tanks spaced in air by [sup 252]Cf-<span class="hlt">source</span>-driven <span class="hlt">noise</span> analysis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The subcritical neutron multiplication factors k for two parallel, axially separated, flat cylindrical tanks separated up to 57.91cm in air and containing enriched uranyl (93.1 wt% [sup 235]U) nitrate solution (71.6-cm-i.d. tanks, 8.91-cm solution thickness, 1.555 g/cm[sup 3] solution density, and 404g U/l uranium density) were measured by the [sup 252]Cf-<span class="hlt">source</span>-driven <span class="hlt">noise</span> analysis method with measured k values varying from 0.99 to 0.80. These measurements were performed at the Los Alamos National Laboratory (LANL) Critical Experiments Facility in 1989 and were part of the program of Westinghouse Idaho Nuclear Company (WINCO) to benchmark calculations for the design of the new storage system at Idaho National Engineering Laboratory. Initial subcriticality measurements by the <span class="hlt">source</span>-jerk method at LANL had indicated that at a calculated neutron multiplication factor k = 0.95, the measured k was 0.975. This discrepancy was of concern to WINCO because the new storage facility was being designed with a k limit of 0.95, and thus, half of the criticality safety margin of the storage design was equal to the discrepancy between early measurements and calculations. The [sup 252]Cf-<span class="hlt">source</span>-driven <span class="hlt">noise</span> analysis measurements confirmed the validity of the calculational methods. In addition to providing the neutron multiplication factor from point-kinetics interpretation of the data, these measurements also provided the auto-power and cross-power spectral densities as a function of frequency, which can be calculated directly with recently developed Monte Carlo methods and thus could also be used to validate calculational methods and cross-section sets.</p> <div class="credits"> <p class="dwt_author">Mihalczo, J.T.; Blakeman, E.D.; Pare, V.K.; Valentine, T.E.; Auslander, D.J. (Oak Ridge National Lab., TN (United States))</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">396</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50427473"> <span id="translatedtitle">2D DOA estimation with propagator method for correlated <span class="hlt">sources</span> under unknown symmetric Toeplitz <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The paper employs the propagator method (PM) to find two-dimensional (2D) direction of arrival angles (DOAs). The proposed algorithm can be applied to the situation when the incident <span class="hlt">sources</span> are mixed, either with uncorrelated or fully correlated (coherent) <span class="hlt">sources</span>. Like S. Pasad et al. (see IEEE Trans., vol.ASSP-36, no.5, p.631-41, 1988), we assume a symmetric Toeplitz covariance matrix for the</p> <div class="credits"> <p class="dwt_author">Nizar Tayem; Hyuck M. Kwon</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">397</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1420682"> <span id="translatedtitle"><span class="hlt">Harmonized</span> strategy for breaking the striations in the fluorescent lamp</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A <span class="hlt">harmonized</span> strategy for breaking the striations in the fluorescent lamp is proposed. The <span class="hlt">harmonized</span> circuit (HC) presented is a dependent current <span class="hlt">source</span> and is used to modulate the lamp current by making the amplitudes of the even <span class="hlt">harmonics</span> nearly the same as the neighboring odd <span class="hlt">harmonics</span>. The time and frequency responses of the lamp current without and with HC</p> <div class="credits"> <p class="dwt_author">Guan-Chyun Hsieh; Chang-Hua Lin</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">398</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1988JSV...120..311P"> <span id="translatedtitle">Study into <span class="hlt">sources</span> of wagon <span class="hlt">noise</span>: Measurement of sound energy generated by vehicle bodies and running gear</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The paper describes a series of measurements carried out to identify and quantify the <span class="hlt">sources</span> of sound connected with the bodywork and running gear of railway wagons. Tests were conducted by the S.N.C.F. with the assistance of the METRAVIB Company, in conjunction with the programme of research of ORE Committee C 163 on <span class="hlt">Noise</span> in the Railway Environment (Office for Research and Experiments of the International Union of Railways). Of the two methods adopted for test purposes, one was a conventional technique using a set of omnidirectional microphones placed vertically at vehicle gauge limit, and the other involved near-field interferometry based on the use of a flat acoustic antenna also placed at the edge of the track. The results of the measurements showed that for the 18 wagons of six different types studied, most of the sound energy radiated came from the running gear.</p> <div class="credits"> <p class="dwt_author">Parent de Curzon, E.; Beguet, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">399</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/details.jsp?query_id=0&page=0&ostiID=1001787"> <span id="translatedtitle"><span class="hlt">Harmonic</span> engine</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A high efficiency <span class="hlt">harmonic</span> engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes <span class="hlt">harmonic</span> oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.</p> <div class="credits"> <p class="dwt_author">Bennett, Charles L. (Livermore, CA)</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-10-20</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">400</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=Emergency+AND+communications&id=EJ1004715"> <span id="translatedtitle">Organizational Communication in Emergencies: Using Multiple Channels and <span class="hlt">Sources</span> to Combat <span class="hlt">Noise</span> and Capture Attention</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">|This study relies on information theory, social presence, and <span class="hlt">source</span> credibility to uncover what best helps people grasp the urgency of an emergency. We surveyed a random sample of 1,318 organizational members who received multiple notifications about a large-scale emergency. We found that people who received 3 redundant messages coming through…</p> <div class="credits"> <p class="dwt_author">Stephens, Keri K.; Barrett, Ashley K.; Mahometa, Michael J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_19");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return 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showDiv("page_22");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">401</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51243642"> <span id="translatedtitle">Unsteady flow distortion past blades: <span class="hlt">Sources</span> of <span class="hlt">noise</span> generation in rotating flows</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The objectives of this research were to determine th flow structure and leading- and trailing-edges of blading tin terms of velocity gradients representing pressure <span class="hlt">sources</span> and to employ active and passive control techniques to manipulate crucial phase shifts of vorticity fields past blading. The topics covered include the following: principal physical and theoretical concepts; experimental techniques, generic classes of edge\\/surface</p> <div class="credits"> <p class="dwt_author">D. O. Rockwell; O. Akin; J. H. Kim; S. Konak; J. Kuryla</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">402</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/985835"> <span id="translatedtitle">Nanograting-based compact VUV spectrometer and beam profiler for in-situ characterization of high-order <span class="hlt">harmonic</span> generation light <span class="hlt">sources</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">A compact, versatile device for VUV beam characterization is presented. It combines the functionalities of a VUV spectrometer and a VUV beam profiler in one unit and is entirely supported by a standard DN200 CF flange. The spectrometer employs a silicon nitride transmission nanograting in combination with a micro-channel plate based imaging detector. This enables the simultaneous recording of wavelengths ranging from 10 nm to 80 nm with a resolution of 0.25 nm to 0.13 nm. Spatial beam profiles with diameters up to 10 mm are imaged with 0.1 mm resolution. The setup is equipped with an in-vacuum translation stage that allows for in situ switching between the spectrometer and beam profiler modes and for moving the setup out of the beam. The simple, robust design of the device is well suited for non-intrusive routine characterization of emerging laboratory- and accelerator-based VUV light <span class="hlt">sources</span>. Operation of the device is demonstrated by characterizing the output of a femtosecond high-order <span class="hlt">harmonic</span> generation light <span class="hlt">source</span>.</p> <div class="credits"> <p class="dwt_author">Kornilov, Oleg; Wilcox, Russell; Gessner, Oliver</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-07-09</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">403</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/657409"> <span id="translatedtitle">Influence of <span class="hlt">noise</span> on chaotic laser dynamics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The Nd:YAG laser with an intracavity second <span class="hlt">harmonic</span> generating crystal is a versatile test bed for concepts of nonlinear time series analysis as well as for techniques that have been developed for control of chaotic systems. Quantitative comparisons of experimentally measured time series of the infrared light intensity are made with numerically computed time series from a model derived here from basic principles. These comparisons utilize measures that help to distinguish between low and high dimensional dynamics and thus enhance our understanding of the influence of <span class="hlt">noise</span> <span class="hlt">sources</span> on the emitted laser light. {copyright} {ital 1997} {ital The American Physical Society}</p> <div class="credits"> <p class="dwt_author">Liu, C.; Abarbanel, H.D.I.; Nunes, K., [Department of Physics and Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093 (United States); Roy, R.; Gills, Z., [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Abarbanel, H.D.I., [Marine Physical Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093 (United States); Nunes K., [Department of Physics, University of California, Santa Cruz, California 95064 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">404</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1983aiaa.confT....G"> <span id="translatedtitle">Flight effects on jet <span class="hlt">noise</span> <span class="hlt">sources</span> investigated by model experiments in the DNW</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The axial sound <span class="hlt">source</span> distribution of a subsonic model jet in a windtunnel flow was investigated at several ratios of tunnel velocity to jet velocity (0-0.25) by means of a highly directional microphone system. The tests were conducted in the anechoic testing hall of the German-Dutch Windtunnel (DNW), using its 8m x 6m open test section. The results of these acoustic measurements verify the assumed stretching of the sound-producing region of the jet due to the ambient flow. The observed stretching factors agree well with those deduced from aerodynamic experiments.</p> <div class="credits"> <p class="dwt_author">Grosche, F.-R.; Stiewitt, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">405</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1643073"> <span id="translatedtitle">Single-sensor active <span class="hlt">noise</span> cancellation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Active <span class="hlt">noise</span> cancellation is an approach to <span class="hlt">noise</span> reduction in which a secondary <span class="hlt">noise</span> <span class="hlt">source</span> that destructively interferes with the unwanted <span class="hlt">noise</span> is introduced. In general, active <span class="hlt">noise</span> cancellation systems rely on multiple sensors to measure the unwanted <span class="hlt">noise</span> field and the effect of the cancellation. This paper develops an approach that utilizes a single sensor. The <span class="hlt">noise</span> field is</p> <div class="credits"> <p class="dwt_author">A. V. Oppenheim; E. Weinstein; K. C. Zangi; M. Feder; D. Gauger</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">406</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1739935"> <span id="translatedtitle">ARTSTREAM: a neural network model of auditory scene analysis and <span class="hlt">source</span> segregation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Multiple sound <span class="hlt">sources</span> often contain <span class="hlt">harmonics</span> that overlap and may be degraded by environmental <span class="hlt">noise</span>. The auditory system is capable of teasing apart these <span class="hlt">sources</span> into distinct mental objects, or streams. Such an ‘auditory scene analysis’ enables the brain to solve the cocktail party problem. A neural network model of auditory scene analysis, called the ARTSTREAM model, is presented to</p> <div class="credits"> <p class="dwt_author">Stephen Grossberg; Krishna K. Govindarajan; Lonce L. Wyse; Michael A. Cohen</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">407</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55866149"> <span id="translatedtitle">Application of active <span class="hlt">noise</span> control to model propeller <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The applicability of active <span class="hlt">noise</span> control to reduce cabin <span class="hlt">noise</span> of turboprop aircraft is demonstrated by conducting several laboratory experiments. The principle of active <span class="hlt">noise</span> control is to reduce the <span class="hlt">noise</span> radiated from a primary <span class="hlt">source</span> by superimposing a signal from a secondary <span class="hlt">source</span>, which is made identical in amplitude but opposite in phase to the primary sound signal. A</p> <div class="credits"> <p class="dwt_author">M. Salikuddin; H. K. Tanna; R. H. Burrin; W. E. Carter</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">408</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/5875386"> <span id="translatedtitle">Acoustic <span class="hlt">noise</span> associated with the MOD-1 wind turbine: its <span class="hlt">source</span>, impact, and control</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This report summarizes extensive research by staff of the Solar Energy Research Institute and its subcontractors conducted to establish the origin and possible amelioration of acoustic disturbances associated with the operation of the DOE/NASA MOD-1 wind turbine installed in 1979 near Boone, North Carolina. Results have shown that the <span class="hlt">source</span> of this acoustic annoyance was the transient, unsteady aerodynamic lift imparted to the turbine blades as they passed through the lee wakes of the large, cylindrical tower supports. Nearby residents were annoyed by the low-frequency, acoustic impulses propagated into the structures in which the complainants lived. The situation was aggravated further by a complex sound propagation process controlled by terrain and atmospheric focusing. Several techniques for reducing the abrupt, unsteady blade load transients were researched and are discussed in the report.</p> <div class="credits"> <p class="dwt_author">Kelley, N.D.; McKenna, H.E.; Hemphill, R.R.; Etter, C.L.; Garrelts, R.L.; Linn, N.C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-02-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">409</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005SPIE.5738..380P"> <span id="translatedtitle">A compact, narrow-band, and low-<span class="hlt">noise</span> 800-mW laser <span class="hlt">source</span> at 980 nm</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We report on the development of a new cost-effective, small form-factor laser <span class="hlt">source</span> at a wavelength of 980 nm. The laser module is based on proven technology commonly used for pump laser modules deployed in fiber amplifiers of telecommunication networks. The package uses a state-of-the-art 14-pin butterfly housing with a footprint of 30x15 mm2 with a Fabry-Perot AlGaAs-InGaAs pump laser diode mounted inside having an anti-reflection coating on its front facet. The light is coupled into a single-mode polarization-maintaining fiber with a mode-field diameter of 6.6 micrometer. The spectral properties of the <span class="hlt">source</span> are defined by a fiber Bragg grating (FBG) that provides feedback in a narrow reflection band. The laser back facet and the FBG form a long resonant cavity of 1.7 m length in which laser light with a low coherence length of a few cm is generated. This configuration with the laser being operated in the coherence-collapse regime has the advantage of being robust against variations in the optical path, thus enabling stable and mode-hop free emission. The laser module has the following properties: a continuous-wave fiber output power exceeding 800 mW, a spectral bandwidth of less than 50 pm, a root-mean square power variation of less than 0.2 % from DC to 2 MHz over the entire power operating range, and a polarization extinction ratio of more than 20 dB. This is a compact, low <span class="hlt">noise</span>, high power <span class="hlt">source</span> for frequency conversion with nonlinear optical materials, such as blue light generation.</p> <div class="credits"> <p class="dwt_author">Pliska, Tomas; Matuschek, Nicolai; Troger, Joerg; Schmidt, Berthold; Mohrdiek, Stefan; Harder, Christoph</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">410</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51124192"> <span id="translatedtitle">Computational simulation of rotating <span class="hlt">noise</span> of fan</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">consists of shaft frequency, blade passage frequency (BPF) and their higher <span class="hlt">harmonics</span>. The shaft-order <span class="hlt">noise</span>, which is mainly induced by unbalanced rotating, is often hard to be eliminated. In this paper, the rotating <span class="hlt">noise</span> caused by geometric asymmetry is discussed and predicted. Analytic point force model is firstly used to predict the <span class="hlt">noise</span> at points in different directions. Then a</p> <div class="credits"> <p class="dwt_author">Tao Feng; Jing Wang; Bin Liu; Nan Li; Xue Wu</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">411</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013SPIE.8659E..0DK"> <span id="translatedtitle">A statistical evaluation of low frequency <span class="hlt">noise</span> of in-pixel <span class="hlt">source</span> follower-equivalent transistors with various channel types and body bias</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Both static and low frequency temporal <span class="hlt">noise</span> characteristics were statistically evaluated for in-pixel <span class="hlt">source</span> followerequivalent transistors with various channel types and body bias conditions. The evaluated transistor types were surface channel (SC) and buried channel (BC) transistors with or without isolated wells. The gate width/length of the evaluated transistors was 0.32/0.32 ?m/?m and the gate oxide thickness was 7.6 nm. The BC transistors without isolated well exhibit <span class="hlt">noise</span> distribution having a much lower <span class="hlt">noise</span> level and a steeper slope compared to the SC transistors. For the BC transistors with isolated wells without body bias, the <span class="hlt">noise</span> level increased compared to the BC transistors with body bias. It has been confirmed that the amplitude of random telegraph <span class="hlt">noise</span> has a correlation to subthreshold swing factor (SS) for both BC and SC transistors. The increase of the <span class="hlt">noise</span> level of BC transistors without body bias is due to the increase of the SS originated from a stronger short channel effect.</p> <div class="credits"> <p class="dwt_author">Kuroda, R.; Yonezawa, A.; Teramoto, A.; Li, T.-L.; Tochigi, Y.; Sugawa, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">412</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/61338746"> <span id="translatedtitle">The <span class="hlt">noise</span> of mobile machines used in surface coal mines: operator exposure, <span class="hlt">source</span> diagnosis, potential <span class="hlt">noise</span> control treatments. Open file report (final), June 1976December 1977</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A summary of earlier work is presented indicating that about 25,000 machine operators employed in U.S. surface coal mines (or about 45 pct of all such operators), suffer greater <span class="hlt">noise</span> exposures than are permitted by the Federal Coal Mine Health and Safety Act of 1969, with the predominant fraction of these overexposures ascribable to tracked dozers, wheeled front-end loaders, haulers,</p> <div class="credits"> <p class="dwt_author">E. E. Ungar; D. W. Andersen; M. N. Rubin</p> <p class="dwt_publisher"></p> <p class="publishDate">1978-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">413</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/10641625"> <span id="translatedtitle">Radiated <span class="hlt">noise</span> characteristics of a modern cargo ship</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Extensive measurements were made of the radiated <span class="hlt">noise</span> of M/V OVERSEAS HARRIETTE, a bulk cargo ship (length 173 m, displacement 25 515 tons) powered by a direct-drive low-speed diesel engine-a design representative of many modern merchant ships. The radiated <span class="hlt">noise</span> data show high-level tonal frequencies from the ship's service diesel generator, main engine firing rate, and blade rate <span class="hlt">harmonics</span> due to propeller cavitation. Radiated <span class="hlt">noise</span> directionality measurements indicate that the radiation is generally dipole in form at lower frequencies, as expected. There are some departures from this pattern that may indicate hull interactions. Blade rate <span class="hlt">source</span> level (174 dB re 1 microPa/m at 9 Hz, 16 knots) agrees reasonably well with a model of fundamental blade rate radiation previously reported by Gray and Greeley, but agreement for blade rate <span class="hlt">harmonics</span> is not as good. <span class="hlt">Noise</span> from merchant ships elevates the natural ambient by 20-30 dB in many areas; the effects of this <span class="hlt">noise</span> on the biological environment have not been widely investigated. PMID:10641625</p> <div class="credits"> <p class="dwt_author">Arveson; Vendittis</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">414</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013OptCo.291..116A"> <span id="translatedtitle">Optimal configurations for active polarimetric imaging systems in the presence of different <span class="hlt">sources</span> of Poisson shot <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We address polarimetric imager optimization in the presence of Poisson-distributed <span class="hlt">noise</span> arising from active illumination, passive contribution, and sensor <span class="hlt">noise</span>. This issue is of great importance for designing imagers that reach the fundamental <span class="hlt">noise</span> limit set by shot <span class="hlt">noise</span>. We show that to maximize the contrast between two regions with different polarimetric properties, the illumination has to be either unpolarized, or totally polarized, and the analysis either unpolarized, which amounts to intensity imaging, or purely polarized. We precisely define the domains of optimality of each of these configurations and present examples showing the influence of passive contribution on the contrast in scalar polarimetric imaging.</p> <div class="credits"> <p class="dwt_author">Anna, Guillaume; Goudail, François; Dolfi, Daniel</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">415</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011HEAD...12.1325Y"> <span id="translatedtitle">X-ray QPO And <span class="hlt">Noise</span> In The Atoll <span class="hlt">Sources</span>: Frequency Correlations And Accretion Modes From mHz To KHz</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We have performed a comprehensive analysis of the RXTE observations of several Atoll type neutron star LMXBs and investigated the QPOs and <span class="hlt">noise</span> components in the frequency range from mHz to kHz. We found that the frequency correlations among two or three components can span in a frequency range by about two to three orders of magnitude in individual <span class="hlt">sources</span>, which corresponds to a large dynamic range of the accretion flow. We discuss the implications of the results on the origins of the X-ray QPOs and <span class="hlt">noise</span> and the evolution of the accretion geometry.</p> <div class="credits"> <p class="dwt_author">Yu, Wenfei; Zhang, W.; Tang, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">416</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/19277078"> <span id="translatedtitle">Phase <span class="hlt">noise</span> optimization in temporal phase-shifting digital holography with partial coherence light <span class="hlt">sources</span> and its application in quantitative cell imaging.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">In temporal phase-shifting-based digital holographic microscopy, high-resolution phase contrast imaging requires optimized conditions for hologram recording and phase retrieval. To optimize the phase resolution, for the example of a variable three-step algorithm, a theoretical analysis on statistical errors, digitalization errors, uncorrelated errors, and errors due to a misaligned temporal phase shift is carried out. In a second step the theoretically predicted results are compared to the measured phase <span class="hlt">noise</span> obtained from comparative experimental investigations with several coherent and partially coherent light <span class="hlt">sources</span>. Finally, the applicability for <span class="hlt">noise</span> reduction is demonstrated by quantitative phase contrast imaging of pancreas tumor cells. PMID:19277078</p> <div class="credits"> <p class="dwt_author">Remmersmann, Christian; Stürwald, Stephan; Kemper, Björn; Langehanenberg, Patrik; von Bally, Gert</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-03-10</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">417</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1988JGR....93.4375C"> <span id="translatedtitle">Resonance of a fluid-driven crack: Radiation properties and implications for the <span class="hlt">source</span> of long-period events and <span class="hlt">harmonic</span> tremor</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A dynamic <span class="hlt">source</span> model is presented, in which a three-dimensional crack containing a viscous compressible fluid is excited into resonance by an impulsive pressure transient applied over a small area ?S of the crack surface. The crack excitation depends critically on two dimensionless parameters called the crack stiffness, C = (b/?)(L/d), and viscous damping loss, F = (12?L)/(?ƒd2?), where b is the bulk modulus, ? is the viscosity, ?ƒ is the density of the fluid, ? is the rigidity, ? is the compressional velocity of the solid, L is the crack length, and d is the crack thickness. The first parameter characterizes the ability of the crack to vibrate and shapes the spectral signature of the <span class="hlt">source</span>, and the second quantifies the effect of fluid viscosity on the duration of resonance. Resonance is sustained by a very slow wave trapped in the fluid-filled crack. This guided wave, called the crack wave, is similar to the tube wave propagating in a fluid-filled borehole; it is inversely dispersive, showing a phase velocity that decreases with increasing wavelength, and its wave speed is always lower than the acoustic velocity of the fluid, decreasing rapidly as the crack stiffness increases. The <span class="hlt">source</span> spectrum shows many sharp peaks characterizing the individual modes of vibration of the crack; the variation of spectral shape, both in the number and width of peaks, is surprisingly complex, reflecting the interference between the lateral and longitudinal modes of resonance, as well as nodes for these modes. The far-field spectrum is marked by narrow-band dominant and subdominant peaks that reflect the interaction of the various <span class="hlt">source</span> modes. The frequency of the dominant spectral peak radiated by the <span class="hlt">source</span> is independent of the radiation direction. The frequency, bandwidth, and spacing of the resonant peaks are strongly dependent on the crack stiffness, larger values of the stiffness factor shifting these peaks to lower frequencies and decreasing their bandwidth. The excitation of a particular mode depends on the position of the trigger and on the extent of the crack surface affected by the pressure transient. Fluid viscosity decreases the amplitudes of the main spectral peaks, smears out the finer structure of the spectrum, and greatly reduces the duration of the radiated signal. The energy loss by radiation is stronger for high frequencies, producing a seismic signature that is marked by a high-frequency content near the onset of the signal and dominated by a longer-period component of much longer duration in the signal coda. Such signature is in harmony with those displayed by long-period events observed on active volcanoes and in hydrofracture experiments. The very low velocity which is possible in a crack with high stiffness (C ? 100) also provides an attractive explanation for very long period tremor, such as type 2 tremor at Aso volcano, Japan, without the requirement of an unrealistically large magma container. The standing wave pattern set up on the crack surface by the sustained resonance in the fluid is observable in the near field of the crack, suggesting that the location and extent of the <span class="hlt">source</span> may be estimated from the mapping of the pattern of nodes and antinodes seen in its vicinity. According to the model, the long-period event and <span class="hlt">harmonic</span> tremor share the same <span class="hlt">source</span> but differ in the boundary conditions for fluid flow and in the triggering mechanism setting up the resonance of the <span class="hlt">source</span>, the former being viewed as the impulse response of the tremor generating system and the latter representing the excitation due to more complex forcing functions.</p> <div class="credits"> <p class="dwt_author">Chouet, Bernard</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">418</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N9522992"> <span id="translatedtitle">Covariant <span class="hlt">Harmonic</span> Oscillators and Coupled <span class="hlt">Harmonic</span> Oscillators.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">It is shown that the system of two coupled <span class="hlt">harmonic</span> oscillators shares the basic symmetry properties with the covariant <span class="hlt">harmonic</span> oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in ...</p> <div class="credits"> <p class="dwt_author">D. Han Y. S. Kim M. E. Noz</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">419</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010APS..DPPXO6010K"> <span id="translatedtitle">Demonstration of a Laser-Driven, High Efficiency, Low <span class="hlt">Noise</span> Argon Gas Jet X-Ray <span class="hlt">Source</span>*</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The electromagnetic pulse (EMP) from Ar gas jet plasmas has been measured to be 4x weaker and 20x shorter in time duration than the EMP from solid density plasmas of similar (3 keV) x-ray energy. We irradiated high density (10^20 cm-3 atomic density) supersonic Ar gas jets and solid (6 x 10^22 cm-3 atomic density) plastic C2H2Cl2 targets with an ultra-high intensity (10^19 W/cm^2), petawatt-class 1053 nm laser. Electron spectroscopy shows that the electron distribution leaving the rear side of gas jet targets close to the laser axis is more than 4x higher in number and energy than for solid targets, in spite of the greatly reduced EMP. This suggests that target density is the more decisive factor. Monochromatic x-ray imaging and K-shell x-ray spectroscopy provide additional insight into the nature of the laser-target interaction. With competitive conversion efficiency from laser energy into x-rays, Ar gas jets are a bright and low-<span class="hlt">noise</span> <span class="hlt">source</span> of 3 keV x-rays for plasma diagnostics. *This work was supported by the DOE Plasma Physics Junior Faculty Award Program and was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-ABS-442193</p> <div class="credits"> <p class="dwt_author">Kugland, N. L.; Aurand, B.; Constantin, C. G.; Everson, E. T.; Glenzer, S. H.; Schaeffer, D.; Tauschwitz, A.; Niemann, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">420</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/14363589"> <span id="translatedtitle">The origin and characterization of the primary signal, <span class="hlt">noise</span>, and interference <span class="hlt">sources</span> in the high frequency electrocardiogram</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">An analysis technique was developed that enabled accurate measurement of the spectral and spatial characteristics of the predominant signal, <span class="hlt">noise</span>, and interference components in high frequency electrocardiograms. A selective sampling technique, utilizing the isoelectric interval during the T-P segments, enabled the charactetistics of the internally generated <span class="hlt">noise</span> and external interference to be obtained independently of the heart signal. Using this</p> <div class="credits"> <p class="dwt_author">RICHARD F. SANTOPIETRO</p> <p class="dwt_publisher"></p> <p class="publishDate">1977-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_20");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">421</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50488371"> <span id="translatedtitle">Active Control of Sound Transmission throughWindows with Carbon Nanotube based Transparent Actuators and Moving <span class="hlt">Noise</span> <span class="hlt">Source</span> Identification</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper explores the development of active sound transmission control systems for windows to achieve significant reduction in <span class="hlt">noise</span> transmission. Several fundamental challenges need to be addressed in order to make the development of such <span class="hlt">noise</span> blocking windows feasible. These include the need for a distributed actuation system that is optically transparent and the unavailability of a real-time reference signal</p> <div class="credits"> <p class="dwt_author">X. Yu; R. Rajamani; K. A. Stelson; T. Cui</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">422</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1999PhLA..256..356B"> <span id="translatedtitle">Rectification of different-color <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The approach for generating a broad-band colored <span class="hlt">noise</span> is proposed, which allows the transition between ``red'' and ``green'' <span class="hlt">noise</span>. The rectification of the <span class="hlt">noise</span> with different colors characterized by the net current of a Brownian particle moving in a ratchet-like potential is studied by using the digital simulation. The present <span class="hlt">noise</span> is also compared with the <span class="hlt">harmonic</span> <span class="hlt">noise</span>. The results show that the average current reverses sign when the external <span class="hlt">noise</span> is filtered off in the region of low frequencies to a sufficient extent. Finally, a parameter plane of the <span class="hlt">noise</span> with the numerically estimated line of the current reversal is plotted.</p> <div class="credits"> <p class="dwt_author">Bao, Jing-Dong</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">423</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52823686"> <span id="translatedtitle">Man-made radio <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Unintentional man-made radio-<span class="hlt">noise</span> <span class="hlt">sources</span> are related to automotive <span class="hlt">sources</span>, power transport and generating facilities, industrial equipment, consumer products, lighting systems, medical equipment and electric trains and buses. The distribution of man-made and naturally occurring <span class="hlt">noise</span> <span class="hlt">sources</span> is considered along with automobile ignition system <span class="hlt">noise</span> <span class="hlt">sources</span>, electric-power generation and transmission-line <span class="hlt">noise</span>, and the theory of the envelope statistics of man-made radio</p> <div class="credits"> <p class="dwt_author">E. N. Skomal</p> <p class="dwt_publisher"></p> <p class="publishDate">1978-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">424</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/174678"> <span id="translatedtitle">Inductively coupled plasma spectrometry: <span class="hlt">Noise</span> characteristics of aerosols, application of generalized standard additions method, and Mach disk as an emission <span class="hlt">source</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This dissertation is focused on three problem areas in the performance of inductively coupled plasma (ICP) <span class="hlt">source</span>. The <span class="hlt">noise</span> characteristics of aerosols produced by ICP nebulizers are investigated. A laser beam is scattered by aerosol and detected by a photomultiplier tube and the <span class="hlt">noise</span> amplitude spectrum of the scattered radiation is measured by a spectrum analyzer. Discrete frequency <span class="hlt">noise</span> in the aerosol generated by a Meinhard nebulizer or a direct injection nebulizer is primarily caused by pulsation in the liquid flow from the pump. A Scott-type spray chamber suppresses white <span class="hlt">noise</span>, while a conical, straight-pass spray chamber enhances white <span class="hlt">noise</span>, relative to the <span class="hlt">noise</span> seen from the primary aerosol. Simultaneous correction for both spectral interferences and matrix effects in ICP atomic emission spectrometry (AES) can be accomplished by using the generalized standard additions method (GSAM). Results obtained with the application of the GSAM to the Perkin-Elmer Optima 3000 ICP atomic emission spectrometer are presented. The echelle-based polychromator with segmented-array charge-coupled device detectors enables the direct, visual examination of the overlapping lines Cd (1) 228.802 nm and As (1) 228.812 nm. The slit translation capability allows a large number of data points to be sampled, therefore, the advantage of <span class="hlt">noise</span> averaging is gained. An ICP is extracted into a small quartz vacuum chamber through a sampling orifice in a water-cooled copper plate. Optical emission from the Mach disk region is measured with a new type of echelle spectrometer equipped with two segmented-array charge-coupled-device detectors, with an effort to improve the detection limits for simultaneous multielement analysis by ICP-AES.</p> <div class="credits"> <p class="dwt_author">Shen, Luan</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-10-06</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">425</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23556699"> <span id="translatedtitle">Underwater <span class="hlt">noise</span> of small personal watercraft (jet skis).</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Personal watercraft (water scooters, jet skis) were recorded under water in Bramble Bay, Queensland, Australia. Underwater <span class="hlt">noise</span> emissions consisted of broadband energy between 100 Hz and 10 kHz due to the vibrating bubble cloud generated by the jet stream, overlain with frequency-modulated tonals corresponding to impeller blade rates and <span class="hlt">harmonics</span>. Broadband monopole <span class="hlt">source</span> levels were 149, 137, and 122 dB re 1 ?Pa @ 1 m (5th, 50th, and 95th percentiles). Even though these are lower than those of small propeller-driven boats, it is not necessarily the broadband <span class="hlt">source</span> level that correlates with the bioacoustic impact on marine fauna. PMID:23556699</p> <div class="credits"> <p class="dwt_author">Erbe, Christine</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">426</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53717298"> <span id="translatedtitle"><span class="hlt">Noise</span> prediction technology for CTOL aircraft</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The application of a new aircraft <span class="hlt">noise</span> prediction program to CTOL <span class="hlt">noise</span> prediction is outlined. <span class="hlt">Noise</span> prediction is based on semiempirical methods for each of the propulsive system <span class="hlt">noise</span> <span class="hlt">sources</span>, such as the fan, the combustor, the turbine, and jet mixing, with <span class="hlt">noise</span>-critical parameter values derived from the thermodynamic cycle of the engine. Comparisons of measured and predicted <span class="hlt">noise</span> levels</p> <div class="credits"> <p class="dwt_author">J. P. Raney</p> <p class="dwt_publisher"></p> <p class="publishDate">1978-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">427</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55476001"> <span id="translatedtitle">Aircraft <span class="hlt">noise</span> prediction program theoretical manual, part 2</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Detailed prediction methods for specific aircraft <span class="hlt">noise</span> <span class="hlt">sources</span> are given. These <span class="hlt">sources</span> are airframe <span class="hlt">noise</span>, combustion <span class="hlt">noise</span>, fan <span class="hlt">noise</span>, single and dual stream jet <span class="hlt">noise</span>, and turbine <span class="hlt">noise</span>. Modifications to the NASA methods which comply with the International Civil Aviation Organization standard method for aircraft <span class="hlt">noise</span> prediction are given.</p> <div class="credits"> <p class="dwt_author">W. E. Zorumski</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">428</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18662627"> <span id="translatedtitle">Computation of rotor wake turbulence <span class="hlt">noise</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A major <span class="hlt">source</span> of fan broadband <span class="hlt">noise</span> is the interaction of rotor wake turbulence with the fan outlet guide vanes. A broadband <span class="hlt">noise</span> model that utilizes computed rotor flow turbulence from a Reynolds averaged Navier–Stokes code is used to predict fan broadband <span class="hlt">noise</span> spectra. The <span class="hlt">noise</span> model is employed to examine the broadband <span class="hlt">noise</span> characteristics of the 22-in <span class="hlt">source</span> diagnostic</p> <div class="credits"> <p class="dwt_author">M. Nallasamy; E. Envia</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">429</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52729139"> <span id="translatedtitle">Keno-Nr a Monte Carlo Code Simulating the Californium -252-<span class="hlt">SOURCE</span>-DRIVEN <span class="hlt">Noise</span> Analysis Experimental Method for Determining Subcriticality</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The ^{252}Cf -<span class="hlt">source</span>-driven <span class="hlt">noise</span> analysis (CSDNA) requires the measurement of the cross power spectral density (CPSD) G_ {23}(omega), between a pair of neutron detectors (subscripts 2 and 3) located in or near the fissile assembly, and the CPSDs, G_{12}( omega) and G_{13}( omega), between the neutron detectors and an ionization chamber 1 containing ^{252}Cf also located in or near the</p> <div class="credits"> <p class="dwt_author">Edward Patrick Ficaro</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">430</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/61396167"> <span id="translatedtitle">Subcriticality measurements for two coupled uranyl nitrate solution tanks using ²⁵²Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis methods</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The subcriticality of two interacting solution tanks was determined using ²⁵²Cf-<span class="hlt">source</span>-driven neutron <span class="hlt">noise</span> analysis methods. This work was supported by a program of collaboration between the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan to study aspects of nuclear criticality safety related to the development of fast breeder technology. These experiments were the</p> <div class="credits"> <p class="dwt_author">J. T. Mihalczo; E. D. Blakeman; W. T. King</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">431</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002ASAJ..111.2336V"> <span id="translatedtitle">Dragline <span class="hlt">noise</span> survey</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It is estimated that 70%-90% of miners have enough <span class="hlt">noise</span> induced hearing loss (NIHL) to be classified as a disability (NIOSH, Publication No. 76-172, 1976; Franks, NIOSH Internal Report, 1996). In response, NIOSH is conducting a cross-sectional survey of the mining industry in order to determine the <span class="hlt">sources</span> of mining <span class="hlt">noise</span> and offer recommendations on how to mitigate high <span class="hlt">noise</span> levels, and bring mining operations into compliance with the recent mining <span class="hlt">noise</span> regulation: 30CFR, Part 62. This paper will outline the results from <span class="hlt">noise</span> surveys of eight draglines which operate in above-ground coal mining operations. The data recorded include <span class="hlt">noise</span> dosimetry in conjunction with time-at-task studies and 1/3-octave sound level (Leq, Lmin, and Lmax) measurements. The 1/3-octave band readings were used to create <span class="hlt">noise</span> contour maps which allowed the spatial and frequency information of the <span class="hlt">noise</span> to be considered. Comparison of Lmin and Lmax levels offer insight into the variability of the <span class="hlt">noise</span> levels inside the dragline. The potential for administrative controls is limited due to consistently high <span class="hlt">noise</span> levels throughout the deck. Implementation of engineering controls is also hindered by the size and number of the <span class="hlt">noise</span> <span class="hlt">sources</span> and the frequency content of the <span class="hlt">noise</span>.</p> <div class="credits"> <p class="dwt_author">Vipperman, Jeffrey S.; Bauer, Eric R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">432</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56070851"> <span id="translatedtitle"><span class="hlt">Noise</span> in charge coupled devices</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The four general <span class="hlt">sources</span> of <span class="hlt">noise</span> in CCD are reviewed which are: signal input, signal output, dark current and trapping <span class="hlt">noise</span>. The trapping <span class="hlt">noise</span> in a Surface Channel CCD (SCCD) is mainly due to interface traps and is the dominant <span class="hlt">noise</span> in this device. In the Buried Channel CCD (BCCD), the low density of bulk traps gives much less trapping</p> <div class="credits"> <p class="dwt_author">J. F. Detry; C. T. Sah</p> <p class="dwt_publisher"></p> <p class="publishDate">1978-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">433</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1984PhDT........62D"> <span id="translatedtitle"><span class="hlt">Noise</span> in Semiconductor Devices</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The devices under study are Si JFETs, Si MOSFETs, GaAs MESFETs, and AlGaAs/GaAs MODFETs. For Si JFETs, by way of two gates--one normal control gate and one substrate gate we can minimize the generation-recombination <span class="hlt">noise</span> by proper biasing these two gates to study the 1/f <span class="hlt">noise</span> <span class="hlt">source</span>. Chapter four gives the <span class="hlt">noise</span> studies about MOSFETs both p channel and n channel. We derived the equations for the number fluctuation model and the mobility fluctuation model. The measurements of MOSFETs show presence of the number fluctuation <span class="hlt">noise</span>. We also discuss 1/f <span class="hlt">noise</span> and thermal <span class="hlt">noise</span> in weak inversion, limiting 1/f <span class="hlt">noise</span>, and flicker <span class="hlt">noise</span> related with gate-voltage-dependent mobility. In GaAs MESFETs we observe the 1/f <span class="hlt">noise</span> through diffusion <span class="hlt">noise</span> to thermal <span class="hlt">noise</span>. For the low-frequency diffusion <span class="hlt">noise</span>, the Poole-Frenkel effect gives a shift of the corner frequency and from the <span class="hlt">noise</span> spectra versus temperature, we can deduce the activation energy. At negative gate bias and floating drain the drain shows thermal <span class="hlt">noise</span>, but when the gate is biased positively so that it draws gate current it will contribute excess <span class="hlt">noise</span> to the floating drain. The current <span class="hlt">noise</span> spectra at both the gate and the floating drain show an I('2mV1/V) relationship, which is common for the Schottky barrier diodes. Low frequency <span class="hlt">noise</span> measurements in MODFETs, at a given frequency the equivalent saturated current varies as the square of the applied voltage, as expected for a fluctuating resistor, and saturates when the characteristic saturates. Measurements on ungated devices shine light on the degration factors in MODFETs and locate the <span class="hlt">noise</span> <span class="hlt">sources</span> in MODFETs. Chapter seven is a very practical approach to study the <span class="hlt">noise</span> performance of those devices applied in high frequency applications. It starts from the background of the theory. Then when the device D.C. characterizations, scattering parameters, microwave <span class="hlt">noise</span> figure, thermal <span class="hlt">noise</span> measurement, and low frequency <span class="hlt">noise</span> measurements, one can have a complete characterization of the device and give a real guidance for low <span class="hlt">noise</span> device development.</p> <div class="credits"> <p class="dwt_author">Duh, Kuang-Hann George</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">434</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.compadre.org/Repository/document/ServeFile.cfm?ID=8292&DocID=903"> <span id="translatedtitle">Strange <span class="hlt">Harmonic</span> Oscillator Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The Ejs Strange <span class="hlt">Harmonic</span> Oscillator model displays the motion of two masses connected by a massless rigid rod and the masses may move without friction along two perpendicular rails in a horizontal table. The energy of the oscillator system can be changed via a slider. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Strange <span class="hlt">Harmonic</span> Oscillator model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_oscillations_strange.jar file will run the program if Java is installed. Ejs is a part of the Open <span class="hlt">Source</span> Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for classical mechanics are available. They can be found by searching ComPADRE for Open <span class="hlt">Source</span> Physics, OSP, or Ejs.</p> <div class="credits"> <p class="dwt_author">Aguirregabiria, Juan</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-11-11</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">435</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.compadre.org/Repository/document/ServeFile.cfm?ID=7565&DocID=585"> <span id="translatedtitle">Simple <span class="hlt">Harmonic</span> Oscillator Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The Ejs Simple <span class="hlt">Harmonic</span> Oscillator model displays the dynamics of a ball attached to an ideal spring. The spring is initially stretched and the ball has zero initial velocity. The initial position of the ball can be changed by click-dragging the ball when the simulation is paused. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Simple <span class="hlt">Harmonic</span> Oscillator model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_osc_SHO.jar file will run the program if Java is installed. Ejs is a part of the Open <span class="hlt">Source</span> Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open <span class="hlt">Source</span> Physics, OSP, or Ejs.</p> <div class="credits"> <p class="dwt_author">Christian, Wolfgang</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-07-05</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">436</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1642850"> <span id="translatedtitle">Pitch-scaled estimation of simultaneous voiced and turbulence-<span class="hlt">noise</span> components in speech</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Almost all speech contains simultaneous contributions from more than one acoustic <span class="hlt">source</span> within the speaker's vocal tract. In this paper, we propose a method-the pitch-scaled <span class="hlt">harmonic</span> filter (PSHF)-which aims to separate the voiced and turbulence-<span class="hlt">noise</span> components of the speech signal during phonation, based on a maximum likelihood approach. The PSHF outputs periodic and aperiodic components that are estimates of the</p> <div class="credits"> <p class="dwt_author">Philip J. B. Jackson; Christine H. Shadle</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">437</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1551128"> <span id="translatedtitle"><span class="hlt">Noise</span> equivalent circuit of a semiconductor laser diode</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A small-signal model of a semiconductor laser is extended to include the effects of intrinsic <span class="hlt">noise</span> by adding current and voltage <span class="hlt">noise</span> <span class="hlt">sources</span>. The current <span class="hlt">noise</span> <span class="hlt">source</span> represents the shot <span class="hlt">noise</span> of carrier recombination, while the voltage <span class="hlt">noise</span> <span class="hlt">source</span> represents the random process of simulated emission. The usefulness of the <span class="hlt">noise</span> equivalent circuit is demonstrated by calculating the modulation and</p> <div class="credits"> <p class="dwt_author">CHRISTOPH HARDER; S. Margalit; A. Yariv; J. Katz; J. Shacham</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">438</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011JEI....20b3001T"> <span id="translatedtitle">Color <span class="hlt">harmonization</span> for images</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Color <span class="hlt">harmonization</span> is an artistic technique to adjust a set of colors in order to enhance their visual harmony so that they are aesthetically pleasing in terms of human visual perception. We present a new color <span class="hlt">harmonization</span> method that treats the <span class="hlt">harmonization</span> as a function optimization. For a given image, we derive a cost function based on the observation that pixels in a small window that have similar unharmonic hues should be <span class="hlt">harmonized</span> with similar <span class="hlt">harmonic</span> hues. By minimizing the cost function, we get a <span class="hlt">harmonized</span> image in which the spatial coherence is preserved. A new matching function is proposed to select the best matching <span class="hlt">harmonic</span> schemes, and a new component-based preharmonization strategy is proposed to preserve the hue distribution of the <span class="hlt">harmonized</span> images. Our approach overcomes several shortcomings of the existing color <span class="hlt">harmonization</span> methods. We test our algorithm with a variety of images to demonstrate the effectiveness of our approach.</p> <div class="credits"> <p class="dwt_author">Tang, Zhen; Miao, Zhenjiang; Wan, Yanli; Wang, Zhifei</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">439</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/49855028"> <span id="translatedtitle">Cumulant-based approach to the <span class="hlt">harmonic</span> retrieval problem</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A time-series consisting of sinusoids observed in additive i.i.d. <span class="hlt">noise</span> or in additive colored Gaussian <span class="hlt">noise</span> of unknown spectral density is considered. The number of <span class="hlt">harmonics</span>, as well as their amplitudes and frequencies are determined using the one-dimensional diagonal slice of the fourth-order cumulant. Applications to the detection of cubic phase coupling are discussed</p> <div class="credits"> <p class="dwt_author">Ananthram Swami; Jerry M. Mendel</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">440</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1639217"> <span id="translatedtitle">Cumulant-based approach to <span class="hlt">harmonic</span> retrieval and related problems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A frequently encountered problem in signal processing is that of estimating the frequencies and amplitudes of <span class="hlt">harmonics</span> observed in additive colored Gaussian <span class="hlt">noise</span>. In practice, the observed signals are contaminated with spatially and temporally colored <span class="hlt">noise</span> of unknown power spectral density. A cumulant-based approach to these problems is proposed. The cumulants of complex processes are defined, and it is shown</p> <div class="credits"> <p class="dwt_author">Ananthram Swami; Jerry M. Mendel</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_21");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">441</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1535011"> <span id="translatedtitle">General analysis of <span class="hlt">harmonic</span> transfer through converters</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Harmonic</span> transfer from DC-side to AC-side and vice-versa through a three-phase bridge power converter is treated by using space vectors. The dependency of the relative frequency of a <span class="hlt">harmonic</span> and its sequence (positive\\/negative) is illustrated. It is shown that the derived relationships are valid for both voltage-<span class="hlt">source</span> and current-<span class="hlt">source</span> power conve