共查询到20条相似文献，搜索用时 15 毫秒
1.
H.J. Haubold 《Astrophysics and Space Science》1997,258(1-2):201-218
Wavelet analysis offers an alternative to Fourier based time- series analysis and is particularly useful when spectral features
are time dependent. We analyze the solar neutrino capture rate of the radiochemical Homestake chlorine experiment with abbreviated
Morlet wavelets, using Foster's (AJ, 111,1709(1996)) rescaled wavelet technique. We emphasize the complementarity of wavelet
analysis to Fourier analysis. Wavelet analysis confirms the results of previously undertaken Fourier analysis. The Homestake
data seem to contain a harmonic content with periodicities of 4.76 yr, 1.89 yr, 0.85 yr, and 0.51 yr. Wavelet analysis reveals
that the 4.76 yr and 1.89 yr periods show an almost constant behavior over the 25 yr Homestake data record, while the 0.85
yr and 0.51 yr periods exhibit a transient phenomenon. The analysis does not show strong evidence for a period of the solar
11 yr cycle.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
W. Van Tend 《Solar physics》1979,64(2):229-236
It is shown that the stability analysis of coronae envisaged by Hearn (1975, 1979) does not lead to a unique stable configuration. The chromosphere-corona transition region is inevitably non-steady. Spicules are a manifestation of this. It is suggested that a point to point analysis of energy losses and gains, rather than a stability analysis, can determine the coronal parameters. 相似文献
3.
G. Efstathiou 《Monthly notices of the Royal Astronomical Society》2002,332(1):193-198
A principal-component analysis of cosmic microwave background (CMB) anisotropy measurements is used to investigate degeneracies among cosmological parameters. The results show that a degeneracy with tensor modes – the 'tensor degeneracy'– dominates uncertainties in estimates of the baryon and cold dark matter densities, ω b =Ωb h 2 , ω c =Ωc h 2 , 1 from an analysis of CMB anisotropies alone. The principal-component analysis agrees well with a maximum-likelihood analysis of the observations, identifying the main degeneracy directions and providing an impression of the effective dimensionality of the parameter space. 相似文献
4.
A new model of the atmospheric entry of the Neuschwanstein fireball has been developed. The fireball was photographed in Germany on April 6, 2002, and three fragments of it were found during a subsequent search in the territory predicted according to observations. In this study, the form of the meteoric body is assumed to be a cube with rounded vertices and edges. The estimated mass of the meteoric body at its entry into the atmosphere is close to the literature data obtained using seismic, acoustic, and infrasonic analysis. It is noted that the analysis of this fireball was for the first time made without using the photometric approach. 相似文献
5.
《New Astronomy》2022
Investigating the spatial correlation between different emissions in an extended astrophysical source can provide crucial insights into their physical connection, hence it can be the key to understand the nature of the system. The point-to-point analysis of surface brightness is a reliable method to do such an analysis. In this work we present PT-REX, a software to carry out these studies between radio and X-ray emission in extended sources. We discuss how to reliably carry out this analysis and its limitation and we introduce the Monte Carlo point-to-point analysis, which allows to extend this approach to poorly-resolved sources. Finally we present and discuss the application of our tool to study the diffuse radio emission in a galaxy cluster. 相似文献
6.
The periodogram spectral analysis method applicable to equallyspaced time series is discussed, and the method is tested first with a simulated data series. It is confirmed that this method is effective for noisy series. Then, applying this method to the analysis of the light periods of the quasars 3C 279 and 3C 345 as well as the BL Lac objects OJ 287 and ON 231, we obtain their light periods to be 7.14 yr, 10.00 yr, 11.76 yr and 6.80 yr, respectively. These results obtained by periodogram spectral analysis are consistent with those obtained by the Jurkevich method in the literature. We have analyzed the effects of different window functions, and commented on their correct selection in practical applications. 相似文献
7.
Claude Froeschlé Robert Gonczi Elena Lega Ugo Locatelli 《Celestial Mechanics and Dynamical Astronomy》1997,69(1-2):235-254
The study of the stochasticity of the asteroid belt requires the analysis of a large number of orbits. We detect the dynamical
character of a set of 5 400 asteroids using the Fast Lyapunov Indicator, a method of analysis closely related to the computation
of the Lyapunov Characteristic Exponents, but cheaper in computational time. For both regular and chaotic orbits we try to
associate the motion to the underlying resonances network. For it we consider different methods of classification of rational
numbers proposed by number theory, and we choose the one which seems to be strictly related to the dynamical behaviour of
a system.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Hai-Hong Wang Lin Liu Department of Astronomy Nanjing University Nanjing Institute for Space Environment Astrodynamics Nanjing University Nanjing 《中国天文和天体物理学报》2005,5(6):665-670
A detailed theoretical analysis on the orbital lifetime and orbital inclination of a Low Moon-Orbiting satellite (LMOs) and the 'stable areas' of long orbital lifetime are given. Numerical simulations under the real force model were carried out, which not only validate the theoretical analysis and also give some valuable results for the orbit design of the LMOs. 相似文献
9.
The Fourier analysis of the argon-37 production rate for runs 18–80 observed in Davis's well-known solar neutrino experiment is presented. The method of Fourier analysis with the unequally-spaced data of Davis and associates is described and the discovered periods are compared with recently published results for the analysis of the data of runs 18–69. The harmonic analysis of the data of runs 18–80 shows time variations of the solar neutrino flux with periods =8.33, 5.26, 2.13, 1.56, 0.83, 0.64, 0.54, and 0.50 yr, respectively, which confirms earlier computations. 相似文献
10.
《Physics and Chemistry of the Earth, Part C: Solar, Terrestrial & Planetary Science》2000,25(4):319-325
Limits of day-to-day variability of MUF as a function of level 'of solar activity, time of day and geographic latitude are given in the ITU-R recommendations. However, these reference values are derived from the analysis of data collected in the American zone three decades ago. In this work an investigation of the hourly daily values of MUF collected in the European area is attained and new bounds of MUF variability are derived. Examples of observed daily measurement data not used in the analysis and predicted ones are reported. The comparison shows that the proposed reference figures are acceptable on the whole. 相似文献
11.
有限元分析技术在空间太阳望远镜结构设计中的应用 总被引：2，自引：0，他引：2
有限元分析技术是现代工程领域中进行结构分析的一种数值方法，已经广泛应用于天文仪器设计。它可使设计者了解被设计对象相应的特性，发现强度或刚度等方面的薄弱点，从而改进和优化设计。以空间太阳望远镜主桁架和主镜室的设计为例，从几何建模、单元划分入手，对静力学分析、模态分析、动态响应和热分析等各方面在空间太阳望远镜设计中的应用进行了阐述；分析了有限元分析存在的误差、产生的原因以及如何减少误差；叙述了有限元分析技术应用于天文仪器尤其是空间天文仪器的发展趋势。 相似文献
12.
R.F.G. Wyse 《Astronomische Nachrichten》2010,331(5):526-534
The kinematics and elemental abundances of resolved stars in the nearby Universe can be used to infer conditions at high redshift, trace how galaxies evolve and constrain the nature of dark matter. This approach is complementary to direct study of systems at high redshift, but I will show that analysis of individual stars allows one to break degeneracies, such as between star formation rate and stellar Initial Mass Function, that complicate the analysis of unresolved, distant galaxies (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
Qualitative analysis is given of the second integrals of the equations of geodesics of the Kerr metric expressed in the Boyer-Lindquist coordinates. 相似文献
14.
The main analytical properties of the generalized Shkarofsky function and a numerical code for its computation are discussed. The results of a numerical analysis are compared with the results of an asymptotic analysis for parameter values relevant to the problem of whistler-mode propagation in the Earth's magnetosphere. This comparison allows us to specify the range of applicability of different approximations to the generalized Shkarofsky function, which have been used for the analysis of relativistic effects on whistler-mode propagation and instability. 相似文献
15.
We describe analysis methods to estimate parameters of electromagnetic waves based on the multi-component measurements of the DEMETER spacecraft. Using the fact that the wave magnetic field is perpendicular to the wave vector, the wave normal direction can be estimated by different methods. We use these plane-wave estimates to interpret measurements of the observed wave emissions. For instance, we use the recently developed singular value decomposition (SVD) technique. The results of the plane-wave analysis have an advantage that they often allow a straightforward interpretation. These different methods have been successfully tested with the data of previous spacecraft. All these methods are also implemented in the analysis tools designed for the analysis of the DEMETER wave measurements.We show the first results of these analysis techniques for different types of wave emissions observed on board DEMETER. Obliquely propagating right-hand polarized electromagnetic waves at a few hundreds of Hz are usually connected with a multi-ion mode structure below the local proton cyclotron frequency and with a sharp lower cutoff of left-hand polarized waves, as well as with right-hand polarized waves tunelling below the multi-ion cross-over frequency. Electron and proton whistlers are also very frequently observed on DEMETER. An unusual narrow-band emission at 140 Hz (well below the local proton cyclotron frequency) serves us as another case for a detailed analysis. We find that these waves are right-hand polarized and obliquely propagating.Using this example case, we also present analysis methods to estimate continuous distribution of wave energy density as a function of wave vector directions. These techniques of wave distribution function (WDF) analysis need both wave and particle measurements. In the analyzed case, two different methods of WDF analysis give similar results consistent with the results of the plane-wave techniques. To identify the source region we use the backward ray-tracing method. The wave normal direction obtained by the analysis of multi-component data is used for a simulation of wave propagation from the point of measurement. By this procedure, we obtain an inverse trajectory of the wave ray. We can thus follow the ray path back to the anticipated source region which is in our case located a few degrees of latitude to the South from the spacecraft position. 相似文献
16.
V. A. Caracatsanis 《Astrophysics and Space Science》1977,47(2):375-384
The aim of this paper has been to carry out an analysis of the light curves of two eclipsing systems TX UMa and S Cnc by Kopal's new method of the analysis of the light curves of eclipsing systems in the frequency domain. The elements of these systems are evaluated and the results are discussed. 相似文献
17.
A. G. Kosovichev 《Solar physics》2006,237(1):1-11
The purpose of this article is to carry out a power-spectrum analysis of the Super-Kamiokande five-day dataset that takes
account of the asymmetry in the error estimates. Whereas for symmetrical error estimates the likelihood analysis involves
a linear optimization procedure, for asymmetrical error estimates it involves a nonlinear optimization procedure. For most
frequencies there is little difference between the power spectra derived from analyses of symmetrized error estimates and
from asymmetrical error estimates, but this is not the case for the principal peak in the power spectrum at 9.43 yr −1. A likelihood analysis that takes account of the error asymmetry leads to a peak with power 13.24 at that frequency, and
a Monte Carlo analysis shows that there is a chance of only 0.1% of finding a peak this big or bigger in the search band 1
– 36 yr −1. From this perspective, power-spectrum analysis that takes account of asymmetry of the error estimates gives evidence for
variability that is significant at the 99.9% level. We comment briefly on an apparent discrepancy between power-spectrum analyses
of the Super-Kamiokande and SNO solar neutrino experiments. 相似文献
18.
L. L. Vanyan Ye. G. Yeroshenko V. N. Lugovenko B. A. Okulesskii A. G. Popov A. L. Kharitonov 《Earth, Moon, and Planets》1977,16(3):289-294
A comparative analysis of the anomalous magnetic field of the Moon, information about which was obtained by the Apollo 15
subsatellite, and the anomalous magnetic field of the Earth, involving data provided from surveys at various altitudes (up
to 500 km) is given. As a result of spectral analysis of these fields it is shown that the main difference of the spectra
is in the lower intensity of long period lunar anomalies and the increased rate of their damping with height, which is probably
connected with the absence of any kind of magnetization by induction. 相似文献
19.
R. L. Duncombe W. J. Klepczynski P. K. Seidelmann 《Celestial Mechanics and Dynamical Astronomy》1971,4(2):224-232
Planetary masses are determined from an extensive analysis of observations of the five outer planets and of seven selected minor planets. 相似文献
20.
Periodic variations in Davis' experimental data concerning the solar neutrino capture rate are derived on the basis of a Fourier spectrum analysis. Variations in the 37Ar production rate are obtained for a series of randomly spaced observations in the period 1970–1985 (runs 18–89). The harmonic analysis of runs 18–89 has determined solar neutrino capture rate variations with periods of 8.33, 5.00, 2.13, 1.61, 0.83, 0.61, 0.54, and 0.51 yr, thereby confirming earlier calculations performed for the set of runs 18–69 (1983), 18–74 (1985a), and 18–80 (1985b). The results also confirm those of Sakurai (1979) who showed that there is strong evidence that the observed solar neutrino flux has a tendency to vary with quasi-biennial periodicity. We show that the results of the Fourier spectrum analysis do not depend upon certain high or low values in Davis' experimental data. 相似文献