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Journal articles on the topic 'Power Specturm'

Author: Grafiati

Published: 1 April 2023

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1

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 (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

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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 (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)

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Koch, Eric W., I.-Da Chiang (江宜達), Dyas Utomo, et al. "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 (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 powe

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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 (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 (

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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 (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

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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 (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, an

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Czarnecki, Mirosław A. "Two-Dimensional Correlation Spectroscopy: The Power of Power Spectra." Applied Spectroscopy 74, no. 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 sp

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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 (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. Thro

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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 (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 f

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Karaçaylı, Naim Göksel, Andreu Font-Ribera та Nikhil Padmanabhan. "Optimal 1D Ly α forest power spectrum estimation – I. DESI-lite spectra". Monthly Notices of the Royal Astronomical Society 497, № 4 (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 estim

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Shi, Feng, Yong-Seon Song, Jacobo Asorey, et al. "HIR4: cosmological signatures imprinted on the cross-correlation between a 21-cm map and galaxy clustering." Monthly Notices of the Royal Astronomical Society 499, no. 4 (2020): 4613–25. http://dx.doi.org/10.1093/mnras/staa2914.

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ABSTRACT We explore the cosmological multitracer synergies between an emission-line galaxy distribution from the Dark Energy Spectroscopic Instrument and a Tianlai Project 21-cm intensity map. We use simulated maps generated from a particle simulation in the light-cone volume (Horizon Run 4), sky-trimmed and including the effects of foreground contamination, its removal and instrument noise. We first validate how the foreground residual affects the recovered 21-cm signal by putting different levels of foreground contamination into the 21-cm maps. We find that the contamination cannot be ignore

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Riazati Seresht, Hamed, Seyed Mohammad Ahadi, and Sanaz Seyedin. "Spectro-temporal Power Spectrum Features for Noise Robust ASR." Circuits, Systems, and Signal Processing 36, no. 8 (2016): 3222–42. http://dx.doi.org/10.1007/s00034-016-0434-0.

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Kim, Dong Sik, and Eunae Lee. "Noise Power Spectrum of Radiography Detectors: I. Measurement Using the Averages of Images." Journal of the Institute of Electronics and Information Engineers 53, no. 12 (2016): 120–27. http://dx.doi.org/10.5573/ieie.2016.53.12.120.

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Lee, Meena, Soonmu Kwon, and Kwon Su Chon. "Analysis of Noise Power Spectrum According to Flat-Field Correction in Digital Radiography." Journal of the Korean Society of Radiology 7, no. 3 (2013): 227–32. http://dx.doi.org/10.7742/jksr.2013.7.3.227.

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Abramenko, Valentina, and Olga Kutsenko. "Magnetic power spectrum in the undisturbed solar photosphere." Acta Astrophysica Taurica 1, no. 1 (2020): 1–5. http://dx.doi.org/10.31059/aat.vol1.iss1.pp1-5.

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Using the magnetic field data obtained with the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO), an investigation of magnetic power spectra in the undisturbed solar photosphere was performed. The results are as follows. 1) To get a reliable estimate of a magnetic power spectrum from the uniformly distributed quiet-sun magnetic flux, a sample pattern of no less than 300 pixels length should be adopted. With smaller patterns, energy on all observable scales might be overestimated. 2) For patterns of different magnetic intensity (e.g., a coronal hole, a quiet-s

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Neyrinck, Mark C. "REJUVENATING THE MATTER POWER SPECTRUM. III. THE COSMOLOGY SENSITIVITY OF GAUSSIANIZED POWER SPECTRA." Astrophysical Journal 742, no. 2 (2011): 91. http://dx.doi.org/10.1088/0004-637x/742/2/91.

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Blake, Chris. "Power spectrum modelling of galaxy and radio intensity maps including observational effects." Monthly Notices of the Royal Astronomical Society 489, no. 1 (2019): 153–67. http://dx.doi.org/10.1093/mnras/stz2145.

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ABSTRACT Fluctuations in the large-scale structure of the Universe contain significant information about cosmological physics, but are modulated in survey data sets by various observational effects. Building on existing literature, we provide a general treatment of how fluctuation power spectra are modified by a position-dependent selection function, noise, weighting, smoothing, pixelization, and discretization. Our work has relevance for the spatial power spectrum analysis of galaxy surveys with spectroscopic or accurate photometric redshifts, and radio intensity-mapping surveys of the sky br

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Yeom, Hong-Gi, Cheol-Hun Han, Ho-Duck Kim, and Kwee-Bo Sim. "Human Emotion Recognition using Power Spectrum of EEG Signals : Application of Bayesian Networks and Relative Power Values." Journal of Korean Institute of Intelligent Systems 18, no. 2 (2008): 251–56. http://dx.doi.org/10.5391/jkiis.2008.18.2.251.

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Chen, Huiguo, Yingmin Li, and Junru Ren. "Fully Nonstationary Spatially Variable Ground Motion Simulations Based on a Time-Varying Power Spectrum Model." Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/293182.

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By analyzing the evolutionary spectrum method for multivariate nonstationary stochastic processes, a simulation method for fully nonstationary spatially variable ground motion is proposed based on the Kameda time-varying power spectrum model. This method can properly simulate nonstationary spatially variable ground motion based on a target response spectrum. Two numerical examples, in which the Kameda time-varying power spectra are calculated for different conditions, are presented to demonstrate the capabilities of the proposed method. In the first example, the nonstationary spatially variabl

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Brown, Timothy M. "Automated p-mode identification using Bayes' theorem." Symposium - International Astronomical Union 123 (1988): 491–94. http://dx.doi.org/10.1017/s0074180900158590.

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The task of interpreting p-mode spectra is complicated by the presence of a very large number of oscillation modes, each of which may appear (because of aliasing) in the power spectra corresponding to several values of l and m. Identifying peaks in a power spectrum with particular modes in an interactive fashion thus quickly becomes impractical. Here I describe an automated method for doing this identification. The method is based on an application of Bayes' theorem, which provides a simple way to use prior knowledge about the oscillation spectrum. The method takes as input the observed power

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Kito, Shuichiro, Koosuke Hattori, Ryo Taguchi, and Taizo Umezaki. "The Feature Extraction Method in Power Spectrum Images for Connector Parts." Journal of the Institute of Industrial Applications Engineers 3, no. 4 (2015): 154–60. http://dx.doi.org/10.12792/jiiae.3.154.

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22

Christian, John T. "Generating Seismic Design Power Spectral Density Functions." Earthquake Spectra 5, no. 2 (1989): 351–68. http://dx.doi.org/10.1193/1.1585526.

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The most widely used way to describe earthquake motions for purposes of design is the response spectrum, but it is often difficult to apply a response spectrum when dealing with multiple degrees of freedom or with complex representations of structural behavior. The power spectral density function, which is a more fundamental description of the frequency content of ground motion, has found increasing use and is essential in the most popular methods of developing artificial earthquake time histories. Although in theory the response spectrum and the power spectral density are closely related, in

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Pal, Srikanta, Pallav Chanda, and Rajib Saha. "Estimation of the Full-sky Power Spectrum between Intermediate and Large Angular Scales from Partial-sky CMB Anisotropies Using an Artificial Neural Network." Astrophysical Journal 945, no. 1 (2023): 77. http://dx.doi.org/10.3847/1538-4357/acb4ee.

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Abstract Reliable extraction of cosmological information from observed cosmic microwave background (CMB) maps may require removal of strongly foreground-contaminated regions from the analysis. In this paper, we employ an artificial neural network (ANN) to predict the full-sky CMB angular power spectrum between intermediate and large angular scales from the partial-sky spectrum obtained from a masked CMB temperature anisotropy map. We use a simple ANN architecture with one hidden layer containing 895 neurons. Using 1.2 × 105 training samples of full-sky and corresponding partial-sky CMB angular

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Brémaud, Pierre, Laurent Massoulié, and Andrea Ridolfi. "Power spectra of random spike fields and related processes." Advances in Applied Probability 37, no. 4 (2005): 1116–46. http://dx.doi.org/10.1239/aap/1134587756.

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In this article, we review known results and present new ones concerning the power spectra of large classes of signals and random fields driven by an underlying point process, such as spatial shot noises (with random impulse response and arbitrary basic stationary point processes described by their Bartlett spectra) and signals or fields sampled at random times or points (where the sampling point process is again quite general). We also obtain the Bartlett spectrum for the general linear Hawkes spatial branching point process (with random fertility rate and general immigrant process described

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Brémaud, Pierre, Laurent Massoulié, and Andrea Ridolfi. "Power spectra of random spike fields and related processes." Advances in Applied Probability 37, no. 04 (2005): 1116–46. http://dx.doi.org/10.1017/s0001867800000690.

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In this article, we review known results and present new ones concerning the power spectra of large classes of signals and random fields driven by an underlying point process, such as spatial shot noises (with random impulse response and arbitrary basic stationary point processes described by their Bartlett spectra) and signals or fields sampled at random times or points (where the sampling point process is again quite general). We also obtain the Bartlett spectrum for the general linear Hawkes spatial branching point process (with random fertility rate and general immigrant process described

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Wiedemann, K. E., J. Unnam, and R. K. Clark. "Computer Program for Deconvoluting Powder Diffraction Spectra." Powder Diffraction 2, no. 3 (1987): 137–45. http://dx.doi.org/10.1017/s0885715600012628.

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AbstractA program is presented that removes broadening from X-ray diffraction spectra. An instrumental spectrum can be used to describe empirically the broadening to be removed, or a Gaussian, Cauchy, or Pearson-VII distribution can be used to analytically describe it. In either case, singlet or doublet forms can be generated. The program returns the deconvoluted spectrum, the reconstructed spectrum, and a sum-of-squares difference between the original and reconstructed spectra. Deconvolution is accomplished using a combination of least-squares, background, and smoothing criteria that minimize

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Persson, P. B., H. Stauss, O. Chung, U. Wittmann, and T. Unger. "Spectrum analysis of sympathetic nerve activity and blood pressure in conscious rats." American Journal of Physiology-Heart and Circulatory Physiology 263, no. 5 (1992): H1348—H1355. http://dx.doi.org/10.1152/ajpheart.1992.263.5.h1348.

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This study tests whether the power spectrum of blood pressure (BP) provides information toward the sympathovagal balance of BP control by comparing the BP (femoral arterial catheter) spectrum with the spectrum of the efferent sympathetic nerve activity (SNA, bipolar electrode around splanchnic nerve). A remarkable resemblance between both spectra was found. A high-frequency component (HF) linked to respiration and a slower fluctuation type between 0.15 and 0.6 Hz (LF) were identified. There was a large and significant coherence only in the HF range of the BP and SNA power spectrum (P < 0.01

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Grosjean, Mathieu, Marc-Antoine Dupret, Kevin Belkacem, Josefina Montalbán, and Reza Samadi. "Energy of solar-like oscillations in red giants." Proceedings of the International Astronomical Union 9, S301 (2013): 341–44. http://dx.doi.org/10.1017/s1743921313014555.

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AbstractCoRoT and Kepler observations of red giants reveal a large variety of spectra of nonradial solar-like oscillations. So far, we understood pretty well the link between the global properties of the star (radius, mass, evolutionary state) and the properties of the oscillation spectrum (Δν, νmax, period spacing). We are interested here in the theoretical predictions of two other components of a power spectrum, the mode linewidths and heights. The study of the energy of the oscillations is of great importance to predict the peak parameters in the power spectrum. We will discuss circumstance

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Lanciani, A., S. Mariani, M. Casaioli, C. Accadia, and N. Tartaglione. "A multiscale approach for precipitation verification applied to the FORALPS case studies." Advances in Geosciences 16 (April 9, 2008): 3–9. http://dx.doi.org/10.5194/adgeo-16-3-2008.

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Abstract. Multiscale methods, such as the power spectrum, are suitable diagnostic tools for studying the second order statistics of a gridded field. For instance, in the case of Numerical Weather Prediction models, a drop in the power spectrum for a given scale indicates the inability of the model to reproduce the variance of the phenomenon below the correspondent spatial scale. Hence, these statistics provide an insight into the real resolution of a gridded field and must be accurately known for interpolation and downscaling purposes. In this work, belonging to the EU INTERREG IIIB Alpine Spa

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Treumann, Rudolf A., Wolfgang Baumjohann, and Yasuhito Narita. "On the ion-inertial-range density-power spectra in solar wind turbulence." Annales Geophysicae 37, no. 2 (2019): 183–99. http://dx.doi.org/10.5194/angeo-37-183-2019.

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Abstract. A model-independent first-principle first-order investigation of the shape of turbulent density-power spectra in the ion-inertial range of the solar wind at 1 AU is presented. Demagnetised ions in the ion-inertial range of quasi-neutral plasmas respond to Kolmogorov (K) or Iroshnikov–Kraichnan (IK) inertial-range velocity–turbulence power spectra via the spectrum of the velocity–turbulence-related random-mean-square induction–electric field. Maintenance of electrical quasi-neutrality by the ions causes deformations in the power spectral density of the turbulent density fluctuations.

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Cai, Jian-hua. "Fault diagnosis of rolling bearing based on empirical mode decomposition and higher order statistics." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 9 (2014): 1630–38. http://dx.doi.org/10.1177/0954406214545820.

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In order to solve the problem of the faulted rolling bearing signal getting easily affected by Gaussian noise, a new fault diagnosis method was proposed based on empirical mode decomposition and high-order statistics. Firstly, the vibration signal was decomposed by empirical mode decomposition and the correlation coefficient of each intrinsic mode function was calculated. These intrinsic mode function components, which have a big correlation coefficient, were selected to estimate its higher order spectrum. Then based on the higher order statistics theory, this method uses higher order spectrum

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Edwards, Timothy S. "Power Delivered to Mechanical Systems by Random Vibrations." Shock and Vibration 16, no. 3 (2009): 261–71. http://dx.doi.org/10.1155/2009/457216.

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This paper develops deformational response power descriptions of multiple degree-of-freedom systems due to stationary random vibration excitation. Two new concepts are developed. The deformational response power density (DRPD) can be computed when a structure's natural frequencies and modal masses are available. The DRPD shows the spectral content of the deformational power delivered to a specific structure by the stationary, random excitation. This function can be found through a weighted windowing of the power spectrum of the input acceleration excitation. Deformational response input power

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Day, Aaron, David Tytler, and Bharat Kambalur. "Power spectrum of the flux in the Lyman-alpha forest from high-resolution spectra of 87 QSOs." Monthly Notices of the Royal Astronomical Society 489, no. 2 (2019): 2536–54. http://dx.doi.org/10.1093/mnras/stz2214.

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Abstract We measure and calibrate the power spectrum of the flux in the Ly α forest at 1.8 &lt; z &lt; 4.6 for wavenumbers 0.003 ≤ k ≤ 0.1 s km−1 from the spectra of 87 QSOs obtained with HIRES on the Keck-I telescope. This is the largest sample using high-resolution spectra, yielding the smallest statistical errors, and we have applied calibrations to reduce new systematic errors. We fit Voigt profiles to the damped Ly α absorbers and we remove them. We subtract metal lines statistically based on metal absorption on the red side of the Ly α emission peak. We find that when performing

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Pelgrims, V., E. Ntormousi, and K. Tassis. "The effect of cosmic variance on the characteristics of dust polarization power spectra." Astronomy & Astrophysics 658 (February 2022): A134. http://dx.doi.org/10.1051/0004-6361/202141879.

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In the context of cosmic microwave background polarization studies and the characterization of the Galactic foregrounds, the power spectrum analysis of the thermal dust polarization sky has led to intriguing evidence of an E∕B asymmetry and a positive TE correlation. In this work, we produce synthesized dust polarization maps from a set of global magneto-hydrodynamic (MHD) simulations of Milky-Way-sized galaxies, and analyze their power spectra at intermediate angular scales (intermediate angular multipoles ℓ∈[60, 140]). We study the role of the initial configuration of the large-scale magneti

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Chang, Zhe, Xukun Zhang, and Jing-Zhi Zhou. "The cosmological vector modes from a monochromatic primordial power spectrum." Journal of Cosmology and Astroparticle Physics 2022, no. 10 (2022): 084. http://dx.doi.org/10.1088/1475-7516/2022/10/084.

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Abstract The cosmological background of higher order vector modes can be generated by the first order scalar perturbations. We investigate the second order and the third order vector modes in a radiation-dominated era systematically. The explicit expressions of two point functions 〈V (n),λ V (n),λ' 〉(n = 2,3) and corresponding power spectra are presented. In the case of a monochromatic primordial power spectrum, the second order vector modes do not exist. However, the third order vector modes can be generated by a monochromatic primordial power spectrum. And it is found that the third order ve

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Parker, M. L., W. N. Alston, Z. Igo, and A. C. Fabian. "Modelling X-ray RMS spectra I: intrinsically variable AGNs." Monthly Notices of the Royal Astronomical Society 492, no. 1 (2019): 1363–69. http://dx.doi.org/10.1093/mnras/stz3470.

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ABSTRACT We present simple xspec models for fitting excess variance spectra of active galactic nuclei. Using a simple Monte Carlo approach, we simulate a range of spectra corresponding to physical parameters varying, then calculate the resulting variance spectra. Starting from a variable power law, we build up a set of models corresponding to the different physical processes that can affect the final excess variance spectrum. We show that the complex excess variance spectrum of IRAS 13224−3809 can be well described by such an intrinsic variability model, where the power-law variability is damp

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Divine, D. V., and F. Godtliebsen. "Bayesian modeling and significant features exploration in wavelet power spectra." Nonlinear Processes in Geophysics 14, no. 1 (2007): 79–88. http://dx.doi.org/10.5194/npg-14-79-2007.

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Abstract. This study proposes and justifies a Bayesian approach to modeling wavelet coefficients and finding statistically significant features in wavelet power spectra. The approach utilizes ideas elaborated in scale-space smoothing methods and wavelet data analysis. We treat each scale of the discrete wavelet decomposition as a sequence of independent random variables and then apply Bayes' rule for constructing the posterior distribution of the smoothed wavelet coefficients. Samples drawn from the posterior are subsequently used for finding the estimate of the true wavelet spectrum at each s

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Pan, Yulin, Brian K. Arbic, Arin D. Nelson, et al. "Numerical Investigation of Mechanisms Underlying Oceanic Internal Gravity Wave Power-Law Spectra." Journal of Physical Oceanography 50, no. 9 (2020): 2713–33. http://dx.doi.org/10.1175/jpo-d-20-0039.1.

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AbstractWe consider the power-law spectra of internal gravity waves in a rotating and stratified ocean. Field measurements have shown considerable variability of spectral slopes compared to the high-wavenumber, high-frequency portion of the Garrett–Munk (GM) spectrum. Theoretical explanations have been developed through wave turbulence theory (WTT), where different power-law solutions of the kinetic equation can be found depending on the mechanisms underlying the nonlinear interactions. Mathematically, these are reflected by the convergence properties of the so-called collision integral (CL) a

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Molina, R. A., J. Retamosa, L. Muñoz, A. Relaño, and E. Faleiro. "Power spectrum of nuclear spectra with missing levels and mixed symmetries." Physics Letters B 644, no. 1 (2007): 25–32. http://dx.doi.org/10.1016/j.physletb.2006.10.058.

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Xu, Long Jun, and Hong Zhi Zhang. "The Uncertainty in Shape Parameter Predictions of Seismic Design Spectra for Nuclear Power Plant." Applied Mechanics and Materials 405-408 (September 2013): 2025–29. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2025.

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Aiming at the uncertainty of design spectrum raised by the construction methods, a comparative study is conducted in which different methodologies performed calculations of seismic response spectra using the same set of ground motion data from recent large earthquakes. The results of the research allowed some estimates to be made of the scaling method and model uncertainty involved in these calculations. These results were compared with the uncertainty derived from the proposed spectrum of a double-parameter-based bi-normalized response spectrum (DPBNS) approach. It is concluded that the sourc

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Gao, Jing, Rihan Wu, and Jinde Zhang. "An Adaptive Multi-Target Jamming Waveform Design Based on Power Minimization." Entropy 22, no. 5 (2020): 508. http://dx.doi.org/10.3390/e22050508.

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With increasing complexity of electronic warfare environments, smart jammers are beginning to play an important role. This study investigates a method of power minimization-based jamming waveform design in the presence of multiple targets, in which the performance of a radar system can be degraded according to the jammers’ different tasks. By establishing an optimization model, the power consumption of the designed jamming spectrum is minimized. The jamming spectrum with power control is constrained by a specified signal-to-interference-plus-noise ratio (SINR) or mutual information (MI) requir

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Choudhury, Madhurima, Abhirup Datta, and Suman Majumdar. "Extracting the 21-cm power spectrum and the reionization parameters from mock data sets using artificial neural networks." Monthly Notices of the Royal Astronomical Society 512, no. 4 (2022): 5010–22. http://dx.doi.org/10.1093/mnras/stac736.

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ABSTRACT Detection of the H i 21-cm power spectrum is one of the key science drivers of several ongoing and upcoming low-frequency radio interferometers. However, the major challenge in such observations come from bright foregrounds, whose accurate removal or avoidance is key to the success of these experiments. In this work, we demonstrate the use of artificial neural networks (ANNs) to extract the H i 21-cm power spectrum from synthetic data sets and extract the reionization parameters from the H i 21-cm power spectrum. For the first time, using a suite of simulations, we present an ANN-base

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Lakshmi, V. Anantha, Satheesh G, and T. Bramhananda Reddy. "Power Spectral Density Estimation and THD of Motor Line Currents of AZSPWM Based DTC of Induction Motor Drive." International Journal of Engineering & Technology 7, no. 4.24 (2018): 42. http://dx.doi.org/10.14419/ijet.v7i4.24.21853.

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Estimating the power distribution over a given frequency range and the total harmonic distortion of the line currents of the AZSPWM based induction motor drive is discussed in this paper. Applying a spectrum analysis on the motor line currents and inspecting the spectrum amplitudes at different switching frequencies for abnormality is a well-known procedure for acoustic noise detection and diagnosis. Among the spectrum analysis techniques for acoustic noise detection, the Fast Fourier Transform (FFT) is the most widely used technique. There are other spectrum techniques, which are based on the

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Ran Tao, Feng Zhang, and Yue Wang. "Fractional Power Spectrum." IEEE Transactions on Signal Processing 56, no. 9 (2008): 4199–206. http://dx.doi.org/10.1109/tsp.2008.925579.

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Asahara, Masaki. "Noise Power Spectrum." Japanese Journal of Radiological Technology 65, no. 12 (2009): 1671–79. http://dx.doi.org/10.6009/jjrt.65.1671.

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Patil, S. P., N. R. Phadnis, and S. A. Patil. "Power Spectrum Analysis." IETE Technical Review 17, no. 3 (2000): 119–21. http://dx.doi.org/10.1080/02564602.2000.11416892.

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Porqueres, Natalia, Alan Heavens, Daniel Mortlock, and Guilhem Lavaux. "Bayesian forward modelling of cosmic shear data." Monthly Notices of the Royal Astronomical Society 502, no. 2 (2021): 3035–44. http://dx.doi.org/10.1093/mnras/stab204.

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ABSTRACT We present a Bayesian hierarchical modelling approach to infer the cosmic matter density field, and the lensing and the matter power spectra, from cosmic shear data. This method uses a physical model of cosmic structure formation to infer physically plausible cosmic structures, which accounts for the non-Gaussian features of the gravitationally evolved matter distribution and light-cone effects. We test and validate our framework with realistic simulated shear data, demonstrating that the method recovers the unbiased matter distribution and the correct lensing and matter power spectru

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Chandra, Rajorshi Sushovan, and Tarun Souradeep. "Primordial Power Spectrum reconstruction from CMB Weak Lensing Power Spectrum." Journal of Cosmology and Astroparticle Physics 2021, no. 10 (2021): 081. http://dx.doi.org/10.1088/1475-7516/2021/10/081.

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Abstract We use the modified and improved Richardson-Lucy (IRL) deconvolution algorithm to reconstruct the Primordial Power Spectrum (PPS) from the Weak Lensing Power Spectrum CL ϕϕ reconstructed from CMB anisotropies. This provides an independent window to observe and constrain the PPS PR (k) along different k scales as compared to CMB Temperature Power Spectrum. The Weak Lensing Power Spectrum does not contain secondary variations in power and hence is cleaner, unlike the Temperature Power Spectrum which suffers from lensing which must be addressed during PPS reconstructions. We demonstrate

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Kim, J. D., Jin Seok Oh, Myung Hyun Lee, and Y. S. Kim. "Spectroscopic Analysis of Plasma Induced in Laser Welding of Aluminum Alloys." Materials Science Forum 449-452 (March 2004): 429–32. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.429.

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This paper describes the features and characteristics of plasma induced in the pulsed YAG laser welding of Al-Mg alloys in air and argon atmospheres. In the air environment, the identified spectra are atomic lines of Al, Mg, Cr, Mn, Fe and Zn, and singly ionized Mg line, as well as strong molecular spectrum of AlO, MgO and AlH. It has been confirmed that the resonant lines of Al and Mg were strongly self-absorbed. These facts have shown that the laser-induced plasma is relatively a low temperature and high density metallic vapor. The intensities of molecular spectra of AlO and MgO are differen

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Philcox, Oliver H. E., and Daniel J. Eisenstein. "Computing the small-scale galaxy power spectrum and bispectrum in configuration space." Monthly Notices of the Royal Astronomical Society 492, no. 1 (2019): 1214–42. http://dx.doi.org/10.1093/mnras/stz3335.

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ABSTRACT We present a new class of estimators for computing small-scale power spectra and bispectra in configuration space via weighted pair and triple counts, with no explicit use of Fourier transforms. Particle counts are truncated at $R_0\sim 100\, h^{-1}\, \mathrm{Mpc}$ via a continuous window function, which has negligible effect on the measured power spectrum multipoles at small scales. This gives a power spectrum algorithm with complexity $\mathcal {O}(NnR_0^3)$ (or $\mathcal {O}(Nn^2R_0^6)$ for the bispectrum), measuring N galaxies with number density n. Our estimators are corrected fo

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