Relevant bibliographies by topics / Power Specturm

Academic literature on the topic 'Power Specturm'

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Published: 1 April 2023

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Journal articles on the topic "Power Specturm"

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Fedi, Maurizio, Tatiana Quarta, and Angelo De Santis. "Inherent power‐law behavior of magnetic field power spectra from a Spector and Grant ensemble." GEOPHYSICS 62, no. 4 (July 1997): 1143–50. http://dx.doi.org/10.1190/1.1444215.

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The Spector and Grant method, which has been in use for 25 years, relates average depths to source to rate of decay of the magnetic power spectra. This method, which assumes a uniform distribution of parameters for an ensemble of magnetized blocks, leads to a depth‐dependent exponential rate of decay. We show that also inherent in this model is a power‐law rate of decay that is independent of depth. For most cases, except for extreme depths and small block sizes, the observed power spectrum should be corrected for a power law decay rate of β∼3. If the depth distribution of the magnetic blocks is Gaussian, then the observed power spectrum should be corrected for both a depth independent power law and exponential decay. This power‐law decay is very similar to the scaling behavior, supposed as a fractal character, of observed magnetic fields in North America. As a general rule, when β∼3, further information is needed to discriminate between a fractal or Spector and Grant model. However, it is becoming quite clear that magnetic power spectra should be corrected for a power law decay before applying the Spector and Grant method for depth determination.
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Deepali, Deepali, and Supratik Banerjee. "Scale-dependent anisotropy of electric field fluctuations in solar wind turbulence." Monthly Notices of the Royal Astronomical Society: Letters 504, no. 1 (March 17, 2021): L1—L6. http://dx.doi.org/10.1093/mnrasl/slab027.

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ABSTRACT We study the variation of average powers and spectral indices of electric field fluctuations with respect to the angle between average flow direction and the mean magnetic field in solar wind turbulence. Cluster spacecraft data from the years 2002 and 2007 are used for the present analysis. We perform a scale-dependent study with respect to the local mean magnetic field using wavelet analysis technique. Prominent anisotropies are found for both the spectral index and power levels of the electric power spectra. Similar to the magnetic field fluctuations, the parallel (or antiparallel) electric fluctuation spectrum is found to be steeper than the perpendicular spectrum. However, the parallel (or antiparallel) electric power is found to be greater than the perpendicular one. Below 0.1 Hz, the slope of the parallel electric power spectra deviates substantially from that of the total magnetic power spectra, supporting the existence of Alfvénic turbulence.
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Koch, Eric W., I.-Da Chiang (江宜達), Dyas Utomo, Jérémy Chastenet, Adam K. Leroy, Erik W. Rosolowsky, and Karin M. Sandstrom. "Spatial power spectra of dust across the Local Group: No constraint on disc scale height." Monthly Notices of the Royal Astronomical Society 492, no. 2 (December 20, 2019): 2663–82. http://dx.doi.org/10.1093/mnras/stz3582.

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ABSTRACT We analyse the 1D spatial power spectra of dust surface density and mid to far-infrared emission at $24\!-\!500\, \mu$m in the LMC, SMC, M31, and M33. By forward-modelling the point spread function (PSF) on the power spectrum, we find that nearly all power spectra have a single power-law and point source component. A broken power-law model is only favoured for the LMC 24 μm MIPS power spectrum and is due to intense dust heating in 30 Doradus. We also test for local power spectrum variations by splitting the LMC and SMC maps into 820 pc boxes. We find significant variations in the power-law index with no strong evidence for breaks. The lack of a ubiquitous break suggests that the spatial power spectrum does not constrain the disc scale height. This contradicts claims of a break where the turbulent motion changes from 3D to 2D. The power spectrum indices in the LMC, SMC, and M31 are similar (2.0–2.5). M33 has a flatter power spectrum (1.3), similar to more distant spiral galaxies with a centrally-concentrated H2 distribution. We compare the power spectra of H i, CO, and dust in M31 and M33, and find that H i power spectra are consistently flatter than CO power spectra. These results cast doubt on the idea that the spatial power spectrum traces large scale turbulent motion in nearby galaxies. Instead, we find that the spatial power spectrum is influenced by (1) the PSF on scales below ∼3 times the FWHM, (2) bright compact regions (30 Doradus), and (3) the global morphology of the tracer (an exponential CO disc).
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Jang, Doyoung, Jongmann Kim, Yong Bae Park, and Hosung Choo. "Study of an Atmospheric Refractivity Estimation from a Clutter Using Genetic Algorithm." Applied Sciences 12, no. 17 (August 26, 2022): 8566. http://dx.doi.org/10.3390/app12178566.

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In this paper, a method for estimating atmospheric refractivity from sea and land clutters is proposed. To estimate the atmospheric refractivity, clutter power spectrums based on an artificial tri-linear model are calculated using an Advanced Refractive Prediction System (AREPS) simulator. Then, the clutter power spectrums are again obtained based on the measured atmospheric refractivity data using the AREPS simulator. In actual operation, this spectrum from measured reflectivity can be replaced with real-time clutter spectrums collected from radars. A cost function for the genetic algorithm (GA) is then defined based on the difference between the two clutter power spectrums to predict the atmospheric refractivity using the artificial tri-linear model. The optimum variables of the tri-linear model are determined at a minimum cost in the GA process. The results demonstrate that atmospheric refractivity can be predicted using the proposed method from the clutter powers.
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Unruh, J. F., and D. D. Kana. "Power/Response Spectrum Transformations in Equipment Qualification." Journal of Pressure Vessel Technology 107, no. 2 (May 1, 1985): 197–202. http://dx.doi.org/10.1115/1.3264434.

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Since its introduction a few years ago the use of the power/response spectrum transformation has gained considerable interest and acceptance, and a number of new applications of the transformation have been developed in the equipment qualification area. A brief review of the power/response spectrum transformation is given with a discussion of the input/output relationships for linear systems required for elevated power spectrum generation. Frequency content of earthquakelike signals is discussed with emphasis on the resolution given by the PSD. The problem of excessive ZPA due to inconsistent spectra enveloping and mechanical nonlinearities is also discussed. The PSD/RS transformation is applied to the problems of combining various dynamic load events, developing bounding spectra, and developing damping consistent test spectra. Development of elevated component spectra corrected for base overtest and generation from in-situ measurements is reviewed.
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Kurita, Toshiki, Masahiro Takada, Takahiro Nishimichi, Ryuichi Takahashi, Ken Osato, and Yosuke Kobayashi. "Power spectrum of halo intrinsic alignments in simulations." Monthly Notices of the Royal Astronomical Society 501, no. 1 (November 25, 2020): 833–52. http://dx.doi.org/10.1093/mnras/staa3625.

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ABSTRACT We use a suite of N-body simulations to study intrinsic alignments (IA) of halo shapes with the surrounding large-scale structure in the ΛCDM model. For this purpose, we develop a novel method to measure multipole moments of the three-dimensional power spectrum of the E-mode field of halo shapes with the matter/halo distribution, $P_{\delta E}^{(\ell)}(k)$ (or $P^{(\ell)}_{{\rm h}E}$), and those of the auto-power spectrum of the E-mode, $P^{(\ell)}_{EE}(k)$, based on the E/B-mode decomposition. The IA power spectra have non-vanishing amplitudes over the linear to non-linear scales, and the large-scale amplitudes at k ≲ 0.1 h−1 Mpc are related to the matter power spectrum via a constant coefficient (AIA), similar to the linear bias parameter of galaxy or halo density field. We find that the cross- and auto-power spectra PδE and PEE at non-linear scales, k ≳ 0.1 h−1 Mpc, show different k-dependences relative to the matter power spectrum, suggesting a violation of the non-linear alignment model commonly used to model contaminations of cosmic shear signals. The IA power spectra exhibit baryon acoustic oscillations, and vary with halo samples of different masses, redshifts, and cosmological parameters (Ωm, S8). The cumulative signal-to-noise ratio for the IA power spectra is about 60 per cent of that for the halo density power spectrum, where the super-sample covariance is found to give a significant contribution to the total covariance. Thus our results demonstrate that the IA power spectra of galaxy shapes, measured from imaging and spectroscopic surveys for an overlapping area of the sky, can be used to probe the underlying matter power spectrum, the primordial curvature perturbations, and cosmological parameters, in addition to the standard galaxy density power spectrum.
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Czarnecki, Mirosław A. "Two-Dimensional Correlation Spectroscopy: The Power of Power Spectra." Applied Spectroscopy 74, no. 8 (June 8, 2020): 894–99. http://dx.doi.org/10.1177/0003702820931156.

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Power spectra are a powerful tool provided by two-dimensional correlation analysis. However, this tool is seldom used in practice. This work shows selected examples of using of the power spectra for the study of various kinds of samples with the aim to promote more common use of this tool. By examination of the power spectrum of specific sample, one can estimate the sensitivity of different molecular fragments on a given perturbation. Determination of the power spectra for smaller data subsets provides information on the dynamics of perturbation-induced spectral changes. If the experimental spectra of different samples in the same perturbation window are recorded, the comparison of the power spectra yields information on differences in the sensitivity of various samples on common perturbation. This possibility is particularly useful for studies of the spectra-structure correlations, interactions, and molecular dynamics. A comparison of the power spectra obtained by using different reference spectra provides information on the nature of spectral changes at different wavenumbers.
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Jackson, Ross A. "Haunted Across the Political Spectrum: The Specter of Communism in Two Midcentury American Organizations." International Journal of Languages, Literature and Linguistics 7, no. 4 (December 2021): 149–56. http://dx.doi.org/10.18178/ijlll.2021.7.4.303.

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Organizations operating in midcentury America experienced a period of relative economic prosperity and global power. While political tensions existed between the United States and the Soviet Union since the culmination of the World War II, when the Soviet Union conducted its first nuclear test in 1949 and then successfully launched Sputnik 1 in 1957, these political tensions became more pressing concerns to American organizations. In fact, the perceived existential threat posed by communism became an observable rhetorical justification for organization and action within the United States. Through the use of corpus linguistics techniques, a comparative analysis was conducted on the foundational documents of the rightwing, John Birch Society and the leftwing, Students for a Democratic Society. Relative word frequencies, collocations, concordancing and statistical analyses were conducted around the use and context of the keyword communism. The results suggest that while these radical and reactionary groups perceived a common threat, multifinality exists in terms of organizational response. This insight is useful to those engaged in strategy development and rhetoric for political and business organizations.
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Cheng, Yun-Ting, and Tzu-Ching Chang. "Cosmic Near-infrared Background Tomography with SPHEREx Using Galaxy Cross-correlations." Astrophysical Journal 925, no. 2 (February 1, 2022): 136. http://dx.doi.org/10.3847/1538-4357/ac3aee.

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Abstract The extragalactic background light (EBL) consists of integrated light from all sources of emission throughout the history of the universe. At near-infrared wavelengths, the EBL is dominated by stellar emission across cosmic time; however, the spectral and redshift information of the emitting sources is entangled and cannot be directly measured by absolute photometry or fluctuation measurements. Cross-correlating near-infrared maps with tracers of known redshift enables EBL redshift tomography, as EBL emission will only correlate with external tracers from the same redshift. Here, we forecast the sensitivity of probing the EBL spectral energy distribution as a function of redshift by cross-correlating the upcoming near-infrared spectro-imaging survey, SPHEREx, with several current and future galaxy redshift surveys. Using a model galaxy luminosity function, we estimate the cross power spectrum clustering amplitude on large scales, and forecast that the near-infrared EBL spectrum can be detected tomographically out to z ∼ 6. We also predict a high-significance measurement (∼102–104 σ) of the small-scale cross power spectrum out to z ∼ 10. The amplitudes of the large-scale cross power spectra can constrain the cosmic evolution of the stellar synthesis process through both continuum and the line emission, while on the nonlinear and Poisson noise scales, the high-sensitivity measurements can probe the mean spectra associated with the tracer population across redshift.
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Karaçaylı, Naim Göksel, Andreu Font-Ribera, and Nikhil Padmanabhan. "Optimal 1D Ly α forest power spectrum estimation – I. DESI-lite spectra." Monthly Notices of the Royal Astronomical Society 497, no. 4 (August 14, 2020): 4742–52. http://dx.doi.org/10.1093/mnras/staa2331.

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ABSTRACT The 1D Ly α forest flux power spectrum P1D is sensitive to scales smaller than a typical galaxy survey, and hence ties to the intergalactic medium’s thermal state, suppression from neutrino masses, and new dark matter models. It has emerged as a competitive framework to study new physics, but also has come with various challenges and systematic errors in analysis. In this work, we revisit the optimal quadratic estimator for P1D, which is robust against the relevant problems such as pixel masking, time evolution within spectrum, and quasar continuum errors. We further improve the estimator by introducing a fiducial power spectrum, which enables us to extract more information by alleviating the discreteness of band powers. We meticulously apply our method to synthetic Dark Energy Spectroscopic Instrument (DESI) spectra and demonstrate how the estimator overcomes each challenge. We further apply an optimization scheme that approximates the Fisher matrix to three elements per row and reduces computation time by 60 per cent. We show that we can achieve per cent precision in P1D with 5-yr DESI data in the absence of systematics and provide forecasts for different spectral qualities.
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Dissertations / Theses on the topic "Power Specturm"

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Borde, Arnaud. "One-Dimensional Power Spectrum and Neutrino Mass in the Spectra of BOSS." Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01023004.

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The framework of the studies presented in this thesis is the one-dimensional power spectrum of the transmitted flux in the Lyman-alpha forests. The Lyman-alpha forest is an an absorption pattern seen in the spectra of high redshift quasars corresponding to the absorption of the quasar light by the hydrogen clouds along the line of sight. It is a powerful cosmological tool as it probes relatively small scales, of the order of a few Mpc. It is also sensible to small non-linear effects such as the one induced by massive neutrinos.First, we have developed two independent methods to measure the one-dimensional power spectrum of the transmitted flux in the Lyman-alpha forest. The first method is based on a Fourier transform, and the second on a maximum likelihood estimator. The two methods are independent and have different systematic uncertainties. The determination of the noise level in the data spectra was subject to a novel treatment, because of its significant impact on the derived power spectrum. We applied the two methods to 13,821 quasar spectra from SDSS-III/BOSS DR9 selected from a larger sample of over 60,000 spectra on the basis of their high quality, large signal-to-noise ratio, and good spectral resolution. The power spectra measured using either approach are in good agreement over all twelve redshift bins from =2.2 to =4.4, and scales from 0.001 (km/s)^−1 to 0.02 (km/s)^−1. We carefully determined the methodological and instrumental systematic uncertainties of our measurements.Then, we present a suite of cosmological N-body simulations with cold dark matter, baryons and neutrinos aiming at modeling the low-density regions of the IGM as probed by the Lyman-alpha forests at high redshift. The simulations are designed to match the requirements imposed by the quality of BOSS and eBOSS data. They are made using either 768^3 or 192^3 particles of each type, spanning volumes ranging from (25 Mpc/h)^3 for high-resolution simulations to (100 Mpc/h)^3 for large-volume ones. Using a splicing technique, the resolution is further enhanced to reach the equivalent of simulations with 3072^3 = 29 billion particles of each type in a (100 Mpc/h)^3 box size, i.e. a mean mass per gas particle of 1.2x10^5 solar masses. We show that the resulting power spectrum is accurate at the 2% level over the full range from a few Mpc to several tens of Mpc. We explore the effect on the one-dimensional transmitted-flux power spectrum of 4 cosmological parameters (n_s, sigma_8, Omega_m ,H_0), 2 astrophysical parameters (T_0, gamma) related to the heating rate of the IGM and the sum of the neutrino masses. By varying the input parameters around a central model chosen to be in agreement with the latest Planck results, we built a grid of simulations that allows the study of the impact on the flux power spectrum of these seven relevant parameters. We improve upon previous studies by not only measuring the effect of each parameter individually, but also probing the impact of the simultaneous variation of each pair of parameters. We thus provide a full second-order expansion, including cross-terms, around our central model. We check the validity of the second-order expansion with independent simulations obtained either with different cosmological parameters or different seeds for the initial condition generation. Finally, a comparison to the one-dimensional Lyman-alpha forest power spectrum obtained in the first part with BOSS data shows an excellent agreement.Eventually, even if there are still some potential biases and systematic errors that need to be studied in our simulation, we performed cosmological fits combining our measurement of the one-dimensional power spectrum and other cosmological probes such as the CMB results provided by Planck. These preliminary results are very encouraging as they lead to some of the tighest cosmological constraints as of today, especially on the sum of the neutrino masses with an upper limit of 0.1 eV.
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Stitz, Elizabeth H. "Instantaneous Power Spectrum." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA229098.

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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, March 1990.
Thesis Advisor(s): Hippenstiel, Ralph D. Second Reader: Cristi, Roberto. "March 1990." Description based on signature page as viewed on August 25, 2009. DTIC Identifier(s): Signal analysis, Time varying spectra, Wigner Ville distribution functions, Rihaczek distribution functions. Author(s) subject terms: Instantaneous Power Spectrum, spectral estimation, nonstationary signal analysis. Includes bibliographical references (p. 108-112). Also available online.
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de, Oliveira Paulo M. D. Monica. "Instantaneous Power Spectrum." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26003.

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The need for tools capable of handling non-stationarities in the spectral content of the data was recognized as early as 1946. The Wigner-Ville Distribution (WD) has been extensively used since its introduction in 1948, but suffers from some associated problems (e.g., spectral cross-terms and requiring the use of analytic signals). An alternative Distribution is proposed, which has its origin in the definition proposed by Page of 'Instantaneous Power Spectrum' (IPS). Its characteristics are examined and, when pertinent, compared to the WD. It is shown to be less sensitive to the problems afflicting the WD, but provides less frequency resolution. The usefulness of a parametric (AR) version is investigated. Some typical test signals are examined, to demonstrate the performance and trade-offs of IPS and its parametric version
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Chiang, Chi-Ting. "Position-dependent power spectrum." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-183996.

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Perkins, Larry D. "Development and characterization of a low power helium microwave induced plasma for spectrometric determinations of metals and nonmetals." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54261.

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This dissertation centers on the development of a new helium microwave induced plasma. The analytical utility of this new plasma source is critically evaluated. To sustain the helium plasma a TM ₀₁₀ high efficiency microwave induced plasma, HEMIP, was used. The HEMIP is a modification of the original Beenakker cavity that precludes the use of external matching devices, such as the highly popular double tuning stub. The He-HEMIP was analytically characterized as an atomization source for metals and nonmetals with the use of atomic emission spectrometry (AES) and atomic fluorescence spectrometry (AFS). A torodial plasma was sustained in the cavity solely by the helium gas output of the nebulizer. Aqueous samples from a pneumatic glass nebulizer/Scott spray chamber were aspirated into the cavity without a desolvation apparatus. With AES, detection limits for metals and nonmetals were in the sub-ppm range. with AFS, detection limits for metals were determined to be in the low ppm to sub-ppb range and were found to be not statistically different from those reported for HCL-ICP-AFS. Linear ranges for AES and AFS ranged from four up to five and one-half orders of concentrative magnitude. The effect of sample uptake rate on the emission intensity was investigated. Ionization interferences were determined to be minimal and phosphate interferences were found not to occur. Development and characterization also included studies of the He-HEMIP's physical characteristics. Excitation and ionization temperatures were found to be approximately equal, suggesting that the He—HEMIP approaches local thermodynamic equilibrium. Evaluation of the He—HEMIP as a routine detector for sulfur during coal pyrolysis and coal extracted samples was investigated. Results showed that the He-HEMIP is selective and sensitive. Detection values compared favorably to those of certified coal samples.
Ph. D.
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Hagerman, Karen Allyn. "Instantaneous power spectrum in 1 1 /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from the National Technical Information Service, 1992. http://edocs.nps.edu/npspubs/scholarly/theses/1992/Jun/92Jun_Hagerman.pdf.

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Tadros-Attalla, Helen. "Power spectrum analysis of redshift surveys." Thesis, University of Oxford, 1996. https://ora.ox.ac.uk/objects/uuid:5a5786db-748e-4c78-bab8-c89a4eda2f07.

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This thesis describes a study of the clustering properties of galaxies and clusters of galaxies as measured by the power spectrum (P(k)) and the counts in cells statistic. The samples used are the optical Stromlo-APM galaxy survey, the APM cluster survey and the IRAS 1.2Jy, QDOT and PSCz surveys. Throughout, N-body simulations, for a variety of cosmological models, are used to test methods and to supplement analytic error estimates. For the Stromlo-APM sample the amplitude of the power spectrum is dependent on galaxy morphology. Early-type galaxies show a higher clustering amplitude than late-type galaxies by a factor of ~ 1.8. There is also tentative evidence for some dependence of the clustering amplitude on galaxy luminosity. The parameter Ω0.6/b is estimated via a comparison with the real-space power spectrum of the two-dimensional APM galaxy survey. For APM clusters the power spectrum is measured to very small wave numbers, with a possible detection of the expected turn-over. The results are inconsistent with the standard cold dark matter model. The shape of P( k) for clusters is approximately the same as that for Stromlo-APM galaxies but amplified by a factor of ~ 3.5. The power spectrum of the QDOT sample depends sensitively on the galaxy weighting scheme, probably due the manner in which the region of the Hercules supercluster is sampled. A best estimate of the power spectrum of IRAS galaxies is computed by combining the IRAS l.2Jy and QDOT samples. The PSCz galaxy power spectrum is also computed. The PSCz galaxies have a clustering amplitude twice that of optical galaxies. A similar result is found from a joint counts in cells analysis. Redshift-space distortions in the PSCz sample are analysed using a spherical harmonic decomposition of the density field. The value of Ω0.6/b = 1 is ruled out by this analysis at the 2σ significance level.
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Griffiths, Louise M. "The cosmic microwave background power spectrum." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249266.

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Duniya, Didam Gwazah Adams. "Relativistic corrections to the power spectrum." University of the Western Cape, 2015. http://hdl.handle.net/11394/4787.

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Philosophiae Doctor - PhD
The matter power spectrum is key to understanding the growth of large-scale structure in the Universe. Upcoming surveys of galaxies in the optical and HI will probe increasingly large scales, approaching and even exceeding the Hubble scale at the survey redshifts. On these cosmological scales, surveys can in principle provide the best constraints on dark energy (DE) and modified gravity models and will be able to test general relativity itself. However, in order to realise the potential of these surveys, we need to ensure that we are using a correct analysis, i.e. a general relativistic analysis, on cosmological scales. There are two fundamental issues underlying the general relativistic (GR) analysis. Firstly, we need to correctly identify the galaxy overdensity that is observed on the past light cone. Secondly, we need to account for all the distortions arising from observing on the past light cone, including redshift distortions (with all general relativistic effects included) and volume distortions. These general elativistic effects appear in the angular power spectra of matter in redshift space. We compute these quantities, taking into account all general relativistic large-scale effects, and including the important contributions from redshift space distortions and lensing convergence. This is done for self-consistent models of DE, known as ‘quintessence’, which have only been very recently treated in the GR approach. Particularly, we focus mainly on computing the predictions (i.e. the power spectra) that need to be confronted with future data. Hence we compute the GR angular power spectra, correcting the 3D Newtonian calculation for several quintessence models. We also compute the observed 3D power spectra for interacting DE (which until now have not previously been studied in the GR approach) – in which dark matter and DE exchange energy and momentum. Interaction in the dark sector can lead to large-scale deviations in the power spectrum, similar to GR effects or modified gravity. For the quintessence case, we found that the DE perturbations make only a small contribution on the largest scales, and a negligible contribution on smaller scales. Ironically, the DE perturbations remove the false boost of large-scale power that arises if we impose the (unphysical) assumption that the DE perturbations vanish. However, for the interacting DE (IDE) case, we found that if relativistic effects are ignored, i.e. if they are not subtracted in order to isolate the IDE effects, the imprint of IDE will be incorrectly identified – which could lead to a bias in constraints on IDE, on horizon scales. Moreover, we found that on super-Hubble scales, GR corrections in the observed galaxy power spectrum are able to distinguish a homogeneous DE (being one whose density perturbation in comoving gauge vanishes) from the concordance model (and from a clustering DE) – at low redshifts and for high magnification bias. Whereas the matter power spectrum is incapable of distinguishing a homogeneous DE from the concordance model. We also found that GR effects become enhanced with decreasing magnification bias, and with increasing redshift.
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Hoi, Loison. "Cosmological inflation and the primordial power spectrum." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:8881/R/?func=dbin-jump-full&object_id=92301.

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Books on the topic "Power Specturm"

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1942-, Kesler Stanislav B., ed. Modern spectrum analysis, II. New York: IEEE Press, 1986.

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Shinozuka, Masanobu. Power spectral density functions compatible with NRC regulatory guide 1.60 response spectra. Washington, DC: Division of Engineering, Division of Reactor Accident Analysis, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1988.

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Ross, Malcolm. Spectre of power. Moncton, N.B: Stronghold Pub. Co., 1987.

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Ross, Malcolm. Spectre of power. Moncton, N.B: Stronghold Pub. Co., 1987.

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Alberta. Alberta Energy and Natural Resources., ed. Alberta in the global energy spectrum. [Edmonton]: Alberta Energy Information Centre, 1989.

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I, Shim Theodore, ed. Spectrum estimation and system identification. New York: Springer-Verlag, 1993.

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Wu, Fan. Game theoretic approaches for spectrum redistribution. New York: Springer, 2014.

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1934-, Williams F. A., and Penner S. S, eds. Modern developments in energy, combustion, and spectroscopy: In honor of S.S. Penner. Oxford, England: Pergamon Press, 1993.

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Kuisma, Mikko. Minimizing conducted RF-emissions in switch mode power supplies using spread-spectrum techniques. Lappeenranta: Lappeenranta University of Technology, 2004.

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E, Dinnebier Robert, and Billinge S. J. L, eds. Powder diffraction: Theory and practice. Cambridge: Royal Society of Chemistry, 2008.

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Book chapters on the topic "Power Specturm"

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McAllister-Williams, R. Hamish, Daniel Bertrand, Hans Rollema, Raymond S. Hurst, Linda P. Spear, Tim C. Kirkham, Thomas Steckler, et al. "Power Spectrum." In Encyclopedia of Psychopharmacology, 1053. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-68706-1_4476.

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Enns, Richard H., and George C. McGuire. "Power Spectrum." In Nonlinear Physics with Mathematica for Scientists and Engineers, 633–36. Boston, MA: Birkhäuser Boston, 2004. http://dx.doi.org/10.1007/978-1-4612-0211-0_40.

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Enns, Richard H., and George McGuire. "Power Spectrum." In Laboratory Manual for Nonlinear Physics with Maple for Scientists and Engineers, 107–9. Boston, MA: Birkhäuser Boston, 1997. http://dx.doi.org/10.1007/978-1-4612-2438-9_22.

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Samani, Afshin. "Power Spectrum." In An Introduction to Signal Processing for Non-Engineers, 39–53. First edition. | Boca Raton, FL : CRC Press/Taylor & Francis Group, 2019.: CRC Press, 2019. http://dx.doi.org/10.1201/9780429263330-6.

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Enns, Richard H., and George C. McGuire. "Power Spectrum." In Nonlinear Physics with Maple for Scientists and Engineers, 605–8. Boston, MA: Birkhäuser Boston, 2000. http://dx.doi.org/10.1007/978-1-4612-1322-2_37.

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Vaseghi, Saeed V. "Power Spectrum Estimation." In Advanced Signal Processing and Digital Noise Reduction, 214–41. Wiesbaden: Vieweg+Teubner Verlag, 1996. http://dx.doi.org/10.1007/978-3-322-92773-6_8.

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Robles-Kelly, Antonio, and Cong Phuoc Huynh. "Illuminant Power Spectrum." In Imaging Spectroscopy for Scene Analysis, 53–61. London: Springer London, 2013. http://dx.doi.org/10.1007/978-1-4471-4652-0_5.

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Stüber, Gordon L. "Modulation and Power Spectrum." In Principles of Mobile Communication, 165–229. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-55615-4_4.

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Jekeli, Christopher. "Correlation and Power Spectrum." In Spectral Methods in Geodesy and Geophysics, 201–93. Boca Raton, FL : CRC Press, 2017. | "A science publishers book.": CRC Press, 2017. http://dx.doi.org/10.1201/9781315118659-5.

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Nevanlinna, Olavi. "Spectrum, Resolvent and Power Boundedness." In Convergence of Iterations for Linear Equations, 13–45. Basel: Birkhäuser Basel, 1993. http://dx.doi.org/10.1007/978-3-0348-8547-8_2.

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Conference papers on the topic "Power Specturm"

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McMackin, I., C. Radzewicz, and M. G. Raymer. "Instabilities and chaos in a multimode standing-wave cw dye laser." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.tuj1.

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Experimental and theoretical investigations of a multimode standing-wave cw dye laser have been carried out. For a three-mirror cavity the laser spectrum is found to evolve by discrete transitions, with increasing pump power, between spectra composed of three stable modes to spectra composed of many modes whose amplitudes fluctuate strongly. At low powers there are three stable modes, separated by 2 GHz (8 cavity mode spacings). When the pump power is raised, the separation suddenly jumps to 4 GHz. After a range of power in which the spectrum is unstable, three stable modes again appear, now with a spacing of 8 GHz. A further increase of pump power leads eventually to a quasicontinuous spectrum, with a spectral width corresponding to about 100 cavity mode spacings. The behavior at low powers is caused by the simultaneous presence of spatial hole burning and an extremely weak etalon which arises spuriously from diffuse backscatter from the folding mirror. In a regime corresponding to unstable spectra, we find experimental evidence for deterministic chaos. We also have carried out numerical simulations of this type of laser using realistic parameters and find qualitative agreement with experiment, including the decrease of mode-intensity correlation time with increasing pump Power.
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Smith, Stephen J. "Role of fluctuations in nonlinear optical aberration processes." In International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.wb2.

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The power spectrum of a well-stabilized single-mode laser is deliberately broadened by introducing Gaussian frequency fluctuations in order to synthesize laser power spectra statistically well characterized to all orders. The objective is to carryout fully quantitative investigations of certain nonlinear atomic absorption processes. The results of a calculation of the power spectrum of a carrier frequency modulated by Gaussian noise will be outlined, and the approach to Lorentzian and Gaussian power spectra demonstrated as limiting cases. Experimental methodology for controlling the power spectrum to ~1 GHz from line center is discussed briefly.
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Hennig, Janou, Antonio Carlos Fernandes, Hans Cozijn, and Marcio Maia Domingues. "On the Application of Selected Wave Group Spectra for the Experimental Investigation of Low Frequency Motions of a Moored Structure." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-80127.

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A moored structure shows both wave and low frequency motions in waves. Wave frequency motions are related to the wave elevation and wave power spectrum of the sea state while low frequency motions are driven by wave groups and the corresponding wave group spectrum. Wave power spectra can be calibrated for model tests. The corresponding wave group spectrum follows from the wave power spectrum together with the applied wave seed or phasing of the wave train. Thus, in common practice (both in simulations and model tests), the wave group spectrum follows from the arbitrary choice of a random seed. This can lead to an under- or overestimation of the resulting low frequency motions of the moored object as compared to the theoretical group spectrum. As an alternative approach, the seeds which give the highest and lowest wave group spectra can be applied in the tests. In this paper, first results of model tests with a moored tanker based on an intentional choice of wave group spectra are presented.
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Hennig, Janou, and Jule Scharnke. "Effect of Variations in Calibrated Wave Parameters on Wave Crest and Height Distributions." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20304.

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In common model test practice, wave power spectra are calibrated prior to the actual model tests. The resulting wave crest and height distributions can be determined from the measured wave time traces at different reference location in the basin but they are not calibrated purposely. The corresponding wave group spectra follow from the wave power spectra together with arbitrarily chosen wave seeds applied to the wave trains. As an alternative approach, the seeds which give the highest and lowest wave group spectra can be applied in the tests. In this paper, results of wave measurements in MARIN’s Shallow Water Basin are presented which include a variation in water depth, wave seed (group spectrum) and location of measurement for the same initial wave power spectrum. The resulting wave crest and height distributions at different wave basin locations are analyzed and compared to theoretical distribution functions. A discussion of possible reasons for differences between theory and measurement concludes the investigation.
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Kähkönen, Jukka, and Pentti Varpasuo. "Generation of Response Spectra Compatible Artificial Acceleration Time Histories." In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54187.

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A procedure to generate artificial acceleration time histories compatible with predefined target response spectrum is presented. The procedure is demonstrated with three examples. It was found out that the generated artificial histories yield high quality response spectra for single-damping defined target spectra. A need for method that yields histories matching target spectra defined with multiple damping values was recognized.
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Huang, Xuan, Furui Xiong, Shuai Liu, Huanhuan Qi, Qian Huang, and Ke Zhang. "Research and Application of Different Seismic Analysis Methods in Nuclear Power Equipment." In 2021 28th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/icone28-64605.

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Abstract The integrity and reliability of nuclear power equipment are directly related to nuclear safety. According to ASME safety classification standard, the supports of pressure vessel, main pump and main cooler in reactor coolant system belong to nuclear safety class I and seismic class I. In order to verify the safety of the supports, according to the relevant regulations, it is necessary to carry out seismic analysis. The response spectrum method is based on the modal results, which can more accurately reflect the dynamic characteristics of the structure, so it is widely used in nuclear power engineering. Response spectrum method includes single point response spectrum method and multi-point response spectrum method. The single point response spectrum method uses the same seismic spectrum as the calculation input, which is suitable for the equipment with single support and small span; while the multipoint response spectrum method inputs different seismic spectra at different constraint points, which is suitable for equipment with multiple supports and large span. In this paper, the above two methods are used to carry out the seismic analysis of the main equipment support of the reactor coolant system, and the application of different seismic analysis methods in nuclear power equipment is studied.
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Kuliešaitė, Miglė, Jokūbas Pimpė, Julius Vengelis, and Vygandas Jarutis. "Analysis of nonlinear response using continuum generation in photonic crystal fiber by tunable frequency femtosecond laser pulses." In Advanced Solid State Lasers. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/assl.2022.jtu6a.13.

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Experimental investigation of continuum generation in PCF is presented with tunable frequency femtosecond pump pulses. The dependence of continuum spectra and pulse spectrum widths on pump pulse power at five different pumping wavelengths are analyzed.
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Gamliel, Avshalom, and Nicholas George. "Radiated spectrum from partially correlated dipoles." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.tuo6.

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The effects of source correlations on the radiated spectrum have been discussed in connection with scalar sources. We examine the spectrum of the field radiated by two linear dipoles that are partially correlated. The dipoles are assumed to be linearly polarized in the same direction and have identical spectra. Expressions are derived for the radiated spectrum, the total emitted power, and the directivity. We illustrate our results by calculating the radiated spectrum for some particular choices of the frequency-dependent correlation functions and by comparison with the well- known limiting cases of fully correlated and uncorrelated dipoles.
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Forristall, George Z., Kevin Ewans, Michel Olagnon, and Marc Prevosto. "The West Africa Swell Project (WASP)." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11264.

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The responses of floating systems are sensitive to the detailed shape of the swell portion of the wave spectrum. Knowledge of swell is particularly important for sites off West Africa. The West Africa Swell Project (WASP JIP) was formed to analyze the available data on West African swell. Measurements were obtained from Shell, Ifremer, Chevron and Marathon. Hindcast data came from Oceanweather and the NOAA Wavewatch model. Sites ranging from Nigeria to Namibia were considered. Modeling the dispersion of swell over long distances indicates that the resulting power spectrum will have a triangular or lognormal shape. Sampling variability makes it difficult to distinguish between those shapes or Jonswap or Gaussian forms, but lognormal spectra generally provided good fits. The models also indicate that the width of the spectrum in both frequency and direction should be inversely related to the peak frequency. Fits to the measurements established detailed relationships for each location. Calculating the response of single degree of freedom oscillators to the measured and hindcast spectra produces response spectra which give the maximum response as a function of natural period and damping. Extreme values of system response can be calculated from the response spectra. The largest responses come from uni-modal spectra, and design spectra can be estimated by inflating them.
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Varnier, Françoise, Georges Rasigni, and Nicole Mayani. "Two-dimensional power spectrum of microrough silver thin film surfaces." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.mdd2.

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The surface structure characterization our team has developed for several years (based on microdensitometer analysis of shadowed surface replicas) makes it possible to determine the statistical parameters which describe any microrough surface. In particular, it is easy to compute the power spectrum, which is a 1-D function. How the 2-D power spectrum which characterizes an isotropic rough surface can be computed from the 1-D one is shown here. Then, it is possible to compare—in the low spatial frequency range—the results given by this method with those obtained by optical methods. We present the results we obtained for the 2-D power spectra connected with a large set of microrough silver thin films, the rms height of which varies from 10 to 80 Å. (These silver films were evaporated onto fluoride underlayers.) Results are compared with those obtained by FECO, scattering studies, etc. Moreover, the study of the optical reflectance of these silver films near the surface plasmon makes it possible to compute these 2-D power spectra in another way and to compare their numerical values with the previous results.
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Reports on the topic "Power Specturm"

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Church, E. L., and P. Z. Takacs. BASIC program for power spectrum estimation. Revision. Office of Scientific and Technical Information (OSTI), May 1994. http://dx.doi.org/10.2172/10192650.

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McCallen, R. Power spectrum calculations using the fast Fourier transform. Office of Scientific and Technical Information (OSTI), December 1995. http://dx.doi.org/10.2172/188886.

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Benson, J., and M. Meth. ANALYZING POWER SPECTRUM CALCULATIONS MADE ON THE BOOSTER MMPS. Office of Scientific and Technical Information (OSTI), November 1991. http://dx.doi.org/10.2172/1150601.

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Tangyunyong, Paiboon. CTAP REPORT Commercialization of Power Spectrum Analysis (PSA) Technology. Office of Scientific and Technical Information (OSTI), June 2022. http://dx.doi.org/10.2172/1874426.

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Yang, Xianzhen. Power Spectrum Prediction of Amplified Dual-Band LTE-Advanced Signals. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.6244.

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Bess, John D., Margaret A. Marshall, J. Blair Briggs, Anatoli Tsiboulia, Yevgeniy Rozhikhin, and John T. Mihalczo. Fast Neutron Spectrum Potassium Worth for Space Power Reactor Design Validation. Office of Scientific and Technical Information (OSTI), March 2015. http://dx.doi.org/10.2172/1178060.

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BROCATO, ROBERT W. LDRD 26573 Ultra-Low Power Spread Spectrum Receiver, FY02 Final Report. Office of Scientific and Technical Information (OSTI), October 2002. http://dx.doi.org/10.2172/803295.

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Meth, M., and A. Ratti. Frequency spectrum generated by AGS Booster power swing, heavy ion cycle. Office of Scientific and Technical Information (OSTI), July 1992. http://dx.doi.org/10.2172/7037846.

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Meth, M., and A. Ratti. Frequency spectrum generated by AGS Booster power swing, heavy ion cycle. Office of Scientific and Technical Information (OSTI), January 1988. http://dx.doi.org/10.2172/1150484.

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Meth, M., and A. Ratti. Frequency spectrum generated by AGS Booster power swing, heavy ion cycle. Office of Scientific and Technical Information (OSTI), July 1992. http://dx.doi.org/10.2172/10170255.

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