scholarly journals Алгоритм оцінювання частоти комплексного гармонічного сигналу з сегментацією даних спостережень

2021 ◽  
pp. 69-74
Author(s):  
Олександр Дмитрович Абрамов ◽  
Юлія Володимирівна С’єдіна ◽  
Андрій Юрійович Ніколаєв ◽  
Артем Андрійович Бондарєв
Keyword(s):  
Spectral Analysis ◽  
Maximum Likelihood ◽  
Harmonic Signal ◽  
Digital Processing ◽  
Data Segmentation ◽  
Digital Modeling ◽  
Optimal Technology ◽  
Practical Capacity ◽  
Harmonic Components ◽  
Using Data

The article deals with the technology of estimating the frequency of harmonic components in the presence of additive normal interferences for solving applied problems of spectral analysis. Objective: to develop a methodology for the synthesis of algorithms for determining the frequency of a complex harmonic signal in discrete sections of the process, this is observed when using data segmentation. Objective: to develop the optimal technology for determining the frequency of the hormonal component of the process, provided by a finite number of discrete compartments, according to model representations and requirements that meet the problems of the current state of spectral analysis practice. These results were obtained. The problem of estimating the harmonic frequency from segmented data in the presence of additive Gaussian interference in observations based on the method of maximum likelihood is solved. The processing algorithm and the consequences of digital modeling of the synthesized evaluation technology for a given number of discrete process samples are given. The analysis of both the practical capacity of the technology for determining the assessment and certain qualitative indicators of assessment is performed. Conclusions. The scientific novelty of the obtained results is as follows: further development as a method for solving problems of estimating the frequency of the harmonic signal from a few sample values of the process under conditions of additive normal interference and methods for optimizing the structure of digital processing of observations in data segmentation. The synthesized technology uses one sample of observations to determine the estimates, which ensure the efficiency of information processing in a simple software implementation. The use of segmentation in the technological process of digital processing of observations allows obtaining estimates, the quality of which corresponds to the indicators of maximum likelihood. For unambiguous assessment, there is a need to eliminate ambiguity. Under these conditions, the technology with a given number of samples can significantly solve the range of signal-to-noise ratios at which can be obtained unbiased estimates.

Observation of gliding tremors from the Gulf of Guinea might help solve over 50 year old mystery

2021 ◽  
Author(s):  
Charlotte Bruland ◽  
Sarah Mader ◽  
Céline Hadziioannou
Keyword(s):  
Spectral Analysis ◽  
Volcanic Activity ◽  
Rayleigh Waves ◽  
Spectral Characteristics ◽  
Gulf Of Guinea ◽  
Seismic Amplitude ◽  
Long Period ◽  
Amplitude Spectra ◽  
Using Data ◽  
Over Time

<p>In the 1960's a peak in the seismic amplitude spectra around 26 s was discovered and detected on stations worldwide. The source was located in the Gulf of Guinea, with approximate coordinates (0,0), and was believed to be generated continuously. A source with similar spectral characteristics was discovered near the Vanuatu Islands, at nearly the antipodal location of the Gulf of Guinea source. Since it was located close to the volcanoes in Vanuatu, this source is commonly attributed to magmatic processes. The physical cause of the 26 s microseism, however, remains unclear.</p><p>We investigate the source location and evolution of the 26 s microseim using data from permanent broadband stations in Germany, France and Algeria and temporary arrays in Morocco, Cameroon and Botswana for spectral analysis and 3-C beamforming to get closer to resolving the source mechanism responsible for this enigmatic signal. We find that the signal modulates over time and is not always detectable, but occasionally it becomes so energetic it can be observed on stations worldwide. Such a burst can last for hours or days. The signal is visible on stations globally approximately 30 percent of the time. Our beamforming analysis confirms that the source is located in the Gulf of Guinea, as shown in previous studies, and that the location is temporally stable. Whenever the signal is detectable, both Love and Rayleigh waves are generated. We discover a spectral glide effect associated with the bursts, that so far has not been reported in the literature. </p><p>The spectral glides last for about two days and are observed on stations globally. Although at higher frequencies, very long period tremors and gliding tremors are also observed on volcanoes as Redoubt in Alaska and Arenal in Costa Rica, suggesting that the origin of the 26 s tremor is also volcanic. However, there is no reported volcanic activity in the area where the source appears to be located.</p><p> </p>

Disproportionately Overrepresented: Women in Local Elected Offices

2018 ◽  
Vol 50 (3) ◽  
pp. 165-176 ◽  
Author(s):  
Ethan M. Bernick ◽  
Brianne Heidbreder
Keyword(s):  
United States ◽  
Maximum Likelihood ◽  
Gender Norms ◽  
The United States ◽  
Census Bureau ◽  
National Association ◽  
County Level ◽  
Political Factors ◽  
Using Data ◽  
The U.S

This research examines the position of county clerk, where women are numerically disproportionately over-represented. Using data collected from the National Association of Counties and the U.S. Census Bureau, the models estimate the correlation between the county clerk’s sex and county-level demographic, social, and political factors with maximum likelihood logit estimates. This research suggests that while women are better represented in the office of county clerk across the United States, when compared to other elective offices, this representation may be because this office is not seen as attractive to men and its responsibilities fit within the construct of traditional gender norms.

Vorticity organization in the outer layer of turbulent channels with disturbed walls

2007 ◽  
Vol 591 ◽  
pp. 145-154 ◽  
Author(s):  
OSCAR FLORES ◽  
JAVIER JIMÉNEZ ◽  
JUAN C. DEL ÁLAMO
Keyword(s):  
Spectral Analysis ◽  
Numerical Experiments ◽  
Outer Region ◽  
Reynolds Numbers ◽  
Streamwise Velocity ◽  
The Self ◽  
Average Flow ◽  
Global Modes ◽  
Self Similar ◽  
Using Data

The vortex clusters in the turbulent outer region of rough- and smooth-walled channels, and their associated velocity structures, are compared using data from numerical experiments at friction Reynolds numbers Reτ ≤ 674. The results indicate that the roughness of the wall does not affect their properties, particularly the existence of wall-detached and wall-attached populations, and the self-similar size distribution of the latter. The average flow field conditioned to the attached clusters reveals similar conical structures of low streamwise velocity for the rough- and smooth-walled cases, which eventually grow into the global modes previously identified from spectral analysis. We conclude that the vortex clusters of the turbulent outer region either originate away from the wall, or quickly forget their origin, in agreement with Townsend's similarity hypothesis.

scholarly journals Methods for Stratified Cluster Sampling with Informative Stratification

2007 ◽  
Vol 2007 ◽  
pp. 1-12
Author(s):  
Alastair Scott ◽  
Chris Wild
Keyword(s):  
Maximum Likelihood ◽  
Regression Models ◽  
Population Distribution ◽  
Estimating Equation ◽  
Cluster Sampling ◽  
Likelihood Methods ◽  
Weighted Estimating Equation ◽  
The Family ◽  
Maximum Likelihood Methods ◽  
Using Data

We look at fitting regression models using data from stratified cluster samples when the strata may depend in some way on the observed responses within clusters. One important subclass of examples is that of family studies in genetic epidemiology, where the probability of selecting a family into the study depends on the incidence of disease within the family. We develop the survey-weighted estimating equation approach for this problem, with particular emphasis on the estimation of superpopulation parameters. Full maximum likelihood for this class of problems involves modelling the population distribution of the covariates which is simply not feasible when there are a large number of potential covariates. We discuss efficient semiparametric maximum likelihood methods in which the covariate distribution is left completely unspecified. We further discuss the relative efficiencies of these two approaches.

scholarly journals Convergence Theorems in Multinomial Saturated and Logistic Models

2020 ◽  
Vol 43 (2) ◽  
pp. 211-231
Author(s):  
Erick Orozco-Acosta ◽  
Humberto LLinás-Solano ◽  
Javier Fonseca-Rodríguez
Keyword(s):  
Maximum Likelihood ◽  
Asymptotic Theory ◽  
Theoretical Study ◽  
Logistic Models ◽  
Convergence Theorems ◽  
Response Variable ◽  
Multinomial Models ◽  
Statistical Program ◽  
Using Data ◽  
Information Matrices

In  this  paper,  we  develop  a  theoretical study about the  logistic  and saturated multinomial models when the response  variable takes  one of R ≥ 2 levels.  Several  theorems on the  existence  and  calculations of the  maximum likelihood  (ML)  estimates of the  parameters of both  models  are  presented and  demonstrated. Furthermore, properties are identified and,  based  on an asymptotic  theory,  convergence theorems are  tested for  score  vectors  and information matrices of both  models.  Finally, an application of this  theory is presented and  assessed  using data from the  R statistical program.

AR-modelling bispectrum estimation using data segmentation into coupled records

1994 ◽  
Vol 30 (25) ◽  
pp. 2096-2098 ◽  
Author(s):  
M.C. Carrión ◽  
A. Gallego ◽  
D.P. Ruiz ◽  
J. Portí
Keyword(s):  
Data Segmentation ◽  
Bispectrum Estimation ◽  
Using Data

Digital processing of regional network data

1982 ◽  
Vol 72 (6B) ◽  
pp. S261-S276
Author(s):  
Robert B. Herrmann
Keyword(s):  
Spectral Analysis ◽  
Focal Mechanism ◽  
Digital Processing ◽  
Network Data ◽  
Regional Network ◽  
Velocity Inversion ◽  
Composite Focal Mechanism ◽  
Time Histories ◽  
Seismic Networks ◽  
Digital Time

abstract Much more than hypocenter location can be done with digital time histories obtained from regional seismic networks. Examples are given of how these data can be routinely processed to provide readily accessible intermediate results for subsequent studies, among which are velocity inversion using teleseismic P residuals, composite focal mechanism studies, and spectral analysis. The processing must be designed to be as routine and as complete as possible. Only with these two objectives achieved can the seismic networks be as productive as they should be.

Comparison of Stochastic Identification Techniques for Dynamic Modelling of Plastics Extrusion Processes

1978 ◽  
Vol 192 (1) ◽  
pp. 299-309 ◽  
Author(s):  
A. K. Kochhar ◽  
J. Parnaby
Keyword(s):  
Spectral Analysis ◽  
Maximum Likelihood ◽  
Computer Control ◽  
Dynamic Modelling ◽  
Generalized Least Squares ◽  
Extrusion Process ◽  
Correlation And Spectral Analysis ◽  
Comparison Of The Results ◽  
Identification Techniques ◽  
Plastics Extrusion

The important plastics extrusion process is briefly described and the difficulties of modelling the process from physical considerations are outlined. A number of stochastic process identification techniques, i.e. correlation, spectral analysis, generalized least squares, instrumental variable, correlation matching, maximum likelihood and Box-Jenkins algorithms are briefly reviewed. The results of experimental work carried out on a laboratory plastics extruder, using random perturbations in screw speed, are presented. From a comparison of the results of different identification methods, it is suggested that although correlation and spectral analysis techniques can help in improving the understanding of the process mechanisms, the type of models best suited for high level feed-forward computer control are of the Box-Jenkins and maximum likelihood structural forms.

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