scholarly journals Stellar Image Location with Maximum Correlation Procedure

1995 ◽  
Vol 166 ◽  
pp. 363-363
Author(s):  
Zhu Zi
Keyword(s):  
Observational Data ◽  
Estimation Method ◽  
Positional Accuracy ◽  
Maximum Correlation ◽  
Single Star ◽  
Mathematical Performance ◽  
Location Methods ◽  
Photoelectric Technique ◽  
Correlation Procedure ◽  
Stellar Image

The location method and accuracy analysis has become a very important subject in astrometry since the photoelectric technique was widely applied. The location methods of the stellar images observed with the slit micrometer are discussed in this paper, and a new estimation method called the maximum correlation procedure is presented. This procedure has already been used to process and analyze the observational data. Because of the ideal mathematical performance of the correlation function, the procedure provides us a good way to determine image locations. By means of simulated observations according to the theoretical analysis, we find that the locating accuracy and the limiting magnitude for this method is much higher than those of traditional locating method. For the observational data of about one thousand stars obtained with the Photoelectric Astrolabe at Yunnan Astronomical Observatory, the positional accuracy of a single star using the maximum correlation is improved by 0.045 arcsec over that with the median. The maximum correlation procedure has also increased the data reduction ability for faint star observations with very low signal to noise ratios.

Description and validation of an ECG removal procedure for EMGdi power spectrum analysis

1986 ◽  
Vol 60 (3) ◽  
pp. 1073-1081 ◽  
Author(s):  
S. Levine ◽  
J. Gillen ◽  
P. Weiser ◽  
M. Gillen ◽  
E. Kwatny
Keyword(s):  
Cross Correlation ◽  
Regression Coefficients ◽  
Total Power ◽  
Median Frequency ◽  
Maximum Correlation ◽  
Power Spectral ◽  
Centroid Frequency ◽  
Electrocardiogram Ecg ◽  
Correlation Procedure ◽  
Power Standard

We describe a cross-correlation procedure for removing contaminating electrocardiogram (ECG) complexes from the diaphragmatic electromyogram (EMGdi). First, the operator selects ECG templates from the EMGdi signal during expiratory intervals. Second, these templates are used to locate ECG complexes occurring during inspiratory EMGdi activity. Third, at the point of maximum correlation between the template and these ECG complexes, the template is adjusted in size and offset to “match” the ECG complex, and adjustments are determined by the linear regression coefficients. Finally, the modified template is subtracted from the EMGdi signal. To evaluate our method, we compared the power spectral density (PSD) obtained from processing EMGdi signals by our method with those obtained from the EMGdi signal in which ECG complexes had been removed by gating. Our results indicate that PSD obtained by these two different methods shows no statistically significant differences with respect to the following features: centroid frequency, median frequency, total power, standard deviation, skewness, and kurtosis.

Probing the anisotropy effects on the CPL parametrizations from light-curve SNIa, BAO and OHD datasets

2019 ◽  
Vol 16 (11) ◽  
pp. 1950177 ◽  
Author(s):  
H. Hossienkhani ◽  
N. Azimi ◽  
Z. Zarei
Keyword(s):  
Light Curve ◽  
Observational Data ◽  
Cosmological Parameters ◽  
Estimation Method ◽  
Likelihood Estimation ◽  
Anisotropic Universe ◽  
Type I ◽  
Acoustic Oscillations ◽  
Type Ia ◽  
Best Fit

Recent observers have shown that an anisotropy cosmic expansion may exist. In this work, we study the effects of low anisotropy with Bianchi type I model using the current observational data, which includes the supernova Legacy Survey (SNLS) sample of 238 SN events ([Formula: see text]) and 1048 Pantheon sample confirmed type Ia supernova (SNIa) covering the redshift range [Formula: see text]. Assuming an anisotropic universe, we use the two parametrizations of the dark energy equation-of-state, such as the [Formula: see text] (PA) and [Formula: see text] (PB), and then we fit the SNIa light-curve parameters and free cosmological parameters, simultaneously employing maximum likelihood estimation method. When combining the Baryon Acoustic Oscillations (BAO) and the observational Hubble data (OHD) measurements with the SNLS SN sample, we find [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PA model and [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PB model. When combining also Pantheon data, we obtain [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PA model and [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PB model. The analysis shows that by considering the anisotropy effects, it leads to more best-fit parameters in [Formula: see text]CDM model with the current observational data.

Observational “Facts” of Binary Mass Loss

1970 ◽  
Vol 6 ◽  
pp. 65-94
Author(s):  
Robert H. Koch
Keyword(s):  
Binary System ◽  
Mass Loss ◽  
Observational Data ◽  
Review Paper ◽  
Close Binary ◽  
Single Star ◽  
Binary Component ◽  
Star Evolution ◽  
Loss Of Mass ◽  
Present Understanding

My present understanding of this problem is formulated in a differential fashion: what is the rate of loss of mass from at least one close binary component over and above what it would have to lose were it a single star? This question implies another: is the mass loss that is expected to occur at certain stages of single star evolution inhibited in any way by membership in a binary system? I do not believe we are yet at the stage of being able to answer these questions, and I would like to use this opportunity to scrutinize as critically as possible the observational data and our interpretation of the results that are in hand. A summary of mass loss trends in single stars may be found in the paper by Deutsch (1969) at the 1968 Trieste Conference or alternately in the review paper by Weymann (1963).

Detection of Earth’s Free Oscillations Stimulated by the Mw8.3 Okhotsk Sea Earthquake in 2013 Based on Observational Data of Water-Tube Tiltmeters in Shaanxi Province

2014 ◽  
Vol 568-570 ◽  
pp. 198-202
Author(s):  
Xiao Yi Shao ◽  
Ying Chang Wang ◽  
Xi Chun Xing
Keyword(s):  
Observational Data ◽  
Estimation Method ◽  
Monitoring Network ◽  
Deformation Monitoring ◽  
Shaanxi Province ◽  
Earth Model ◽  
Okhotsk Sea ◽  
Free Oscillations ◽  
Water Tube ◽  
Earth’S Free Oscillations

Using power spectrum density estimation method, analyzed the digital observational data of water-tube tiltmeters of Shaanxi deformation monitoring network in 6 seismic stations as QL, HZ, HY, BJ, XA and NQ, which detected the earth’s free oscillations stimulated by the Mw8.3 Okhotsk Sea Earthquake in May 24th, 2013. The results show that radical shock of spherical oscillation (0S05~0S32), harmonic spherical oscillation (3S01, 1S04, 2S04, 1S06) and toroidal oscillations (0T05~0T09) are detected effectively. Comparing the period of the extracted oscillation with that the theoretical oscillation of the Preliminary Reference Earth Model (PREM), finding that they are accordant with each other and the relative error is less than 0.2%. And the result is consistent with the CDSN Urumqi observatory recorded in M8.1 Kunlun Mountains Earthquake in 2001.

scholarly journals TOWARDS AN ACCURATE LOW-COST STEREO-BASED NAVIGATION OF UNMANNED PLATFORMS IN GNSS-DENIED AREAS

2019 ◽  
Vol XLII-2/W17 ◽  
pp. 323-329
Author(s):  
Z. Shtain ◽  
S. Filin
Keyword(s):  
Pose Estimation ◽  
Inertial Sensors ◽  
Low Cost ◽  
Estimation Method ◽  
Slight Modification ◽  
Bundle Adjustment ◽  
Positional Accuracy ◽  
Accurate Localization ◽  
Vision Sensors ◽  
System Configurations

Abstract. While lightweight stereo vision sensors provide detailed and high-resolution information that allows robust and accurate localization, the computation demands required for such process is doubled compared to monocular sensors. In this paper, an alternative model for pose estimation of stereo sensors is introduced which provides an efficient and precise framework for investigating system configurations and maximize pose accuracies. Using the proposed formulation, we examine the parameters that affect accurate pose estimation and their magnitudes and show that for standard operational altitudes of ∼50 m, a five-fold improvement in localization is reached, from ∼0.4–0.5 m with a single sensor to less than 0.1 m by taking advantage of the extended field of view from both cameras. Furthermore, such improvement is reached using cameras with reduced sensor size which are more affordable. Hence, a dual-camera setup improves not only the pose estimation but also enables to use smaller sensors and reduce the overall system cost. Our analysis shows that even a slight modification in camera directions improves the positional accuracy further and yield attitude angle as accurate as ±6’ (compared to ±20’). The proposed pose estimation method relieves computational demands of traditional bundle adjustment processes and is easily integrated with other inertial sensors.

Current status of special planetary and lunar theories and ephemerides

1966 ◽  
Vol 25 ◽  
pp. 266-267
Author(s):  
R. L. Duncombe
Keyword(s):  
Observational Data ◽  
Current Status ◽  
Numerical Errors

An examination of some specialized lunar and planetary ephemerides has revealed inconsistencies in the adopted planetary masses, the presence of non-gravitational terms, and some outright numerical errors. They should be considered of temporary usefulness only, subject to subsequent amendment as required for the interpretation of observational data.

July 11, 1991 Eclipse Corona Photometry by the Results of Electropolarimetric and CCD-Matrix Observations

1994 ◽  
Vol 144 ◽  
pp. 567-569
Author(s):  
V. Kulidzanishvili ◽  
D. Georgobiani
Keyword(s):  
Solar Corona ◽  
Observational Data ◽  
Solar Limb ◽  
Ccd Matrix

AbstractThe observational data of July 11, 1991 eclipse solar corona obtained by both electropolarimeter (EP) and CCD-matrix were processed. Using these data, the solar corona photometry was carried out. The results of EP data are compared with the ones of CCD data. It must be noted here that the CCD data give us only characteristics of the inner corona, while the EP data show the features of both the inner and middle corona up to 4R⊙. Standard flattening indexϵis evaluated from both data. The dependence of the flattening index on the distance from the solar limb is investigated. The isophotes in Na and Ca lines are plotted. Based on these data some ideas and conclusions on the type of the solar corona are presented.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

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