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151.
???1999??2012???????????????????????????????λ????????????????????????λ??????GPS??????????????????????仯?????????о?????????????λ??GPS????????仯??????????????????仯?????????????????????????????????????λ????????GPS?????????С????ζ??????????????????????λ???????GPS?????????????ζ??????3??????????λ?仯????GPS????????????????г???????? 相似文献
152.
选取中国重力台网14台gPhone弹簧重力仪组成2个观测剖面,对日本本州东海岸附近海域Ms9.0特大地震前(3月1日至10日)的观测数据进行了分析。结果表明:沿海各台站统一出现了喇叭口状的“重力异常扰动”现象,且扰动异常随震中距的增加呈衰减趋势。 相似文献
153.
Douglas Soldan de Oliveira Othon Cabo Winter Ernesto Vieira Neto Gislaine de Felipe 《Earth, Moon, and Planets》2007,100(3-4):233-239
The irregular satellites of Jupiter are believed to be captured asteroids or planetesimals. In the present work is studied
the direction of capture of these objects as a function of their orbital inclination. We performed numerical simulations of
the restricted three-body problem, Sun-Jupiter-particle, taking into account the growth of Jupiter. The integration was made
backward in time. Initially, the particles have orbits as satellites of Jupiter, which has its present mass. Then, the system
evolved with Jupiter losing mass and the satellites escaping from the planet. The reverse of the escape direction corresponds
to the capture direction. The results show that the Lagrangian points L1 and L2 mainly guide the direction of capture. Prograde
satellites are captured through these two gates with very narrow amplitude angles. In the case of retrograde satellites, these
two gates are wider. The capture region increases as the orbital inclination increases. In the case of planar retrograde satellites
the directions of capture cover the whole 360° around Jupiter. We also verified that prograde satellites are captured earlier
in actual time than retrograde ones.
This paper was presented at the Asteriods, Comets and Meteors meeting held at Búzios, Rio de Janeiro, Brazil in August 2005
and could not be included in the special issue related to that conference. 相似文献
154.
The processes of ion acceleration and Alfvén wave generation by accelerated particles at the Earth’s bow shock are studied within a quasi-linear approach. Steady-state ion and wave spectra are shown to be established in a time of 0.3–4 h, depending on the background level of Alfvénic turbulence in the solar wind. The Alfvén waves produced by accelerated ions are confined within the frequency range 10?2–1 Hz and their spectral peak with a wave amplitude βB ~ B comparable to the interplanetary magnetic field strength B corresponds to the frequency v = (2–3) × 10?2 Hz. The high-frequency part of the wave spectrum (v > 0.2 Hz) undergoes damping by thermal ions. The calculated spectra of the accelerated ions and the Alfvén waves generated by them reproduce the main features observed in experiments. 相似文献
155.
Louis M. Barbier Robert Smith Scott Murphy Eric R. Christian Rodger Farley John F. Krizmanic John W. Mitchell Robert E. Streitmatter Eugene C. Loh Stephen Stochaj 《Astroparticle Physics》2005,22(5-6):439-449
We have designed and built an instrument to measure and monitor the “nightglow” of the Earth’s atmosphere in the near ultraviolet (NUV). In this paper we describe the design of this instrument, called NIGHTGLOW. NIGHTGLOW is designed to be flown from a high altitude research balloon, and circumnavigate the globe. NIGHTGLOW is a NASA, University of Utah, and New Mexico State University project. A test flight took place from Palestine, Texas on July 5, 2000, lasting about 8 h. The instrument performed well and landed safely in Stiles, Texas with little damage. The resulting measurements of the NUV nightglow are compared with previous measurements from sounding rockets and balloons. 相似文献
156.
M. A. Vashkov’yak 《Astronomy Letters》2003,29(6):416-423
A modified method for averaging the perturbing function in Hill’s problem is suggested. The averaging is performed in the revolution period of the satellite over the mean anomaly of its motion with a full allowance for a variation in the position of the perturbing body. At its fixed position, the semimajor axis of the satellite orbit during the revolution of the satellite is constant in view of the evolution equations, while the remaining orbital elements undergo secular and long-period perturbations. Therefore, when the motion of the perturbing body is taken into account, the semimajor axis of the satellite orbit undergoes the strongest perturbations. The suggested approach generalizes the averaging method in which only the linear (in time) term is included in the perturbing function. This method requires no expansion in powers of time. The described method is illustrated by calculating the perturbations of the semimajor axes for two distant satellites of Saturn, S/2000 S 1 and S/2000 S5. An approximate analytic solution is compared with the results of numerical integration of the averaged system of equations of motion for these satellites. 相似文献
157.
《New Astronomy》2015
Analysis of long-term solar data from different observatories is required to compare and confirm the various level of solar activity in depth. In this paper, we study the north–south asymmetry of monthly mean sunspot area distribution during the cycle-23 and rising phase of cycle-24 using the data from Kodaikanal Observatory (KO), Michelson Doppler Imager (MDI) and Solar Optical Observing Network (SOON). Our analysis confirmed the double peak behavior of solar cycle-23 and the dominance of southern hemisphere in all the sunspot area data obtained from three different resources. The analysis also showed that there is a 5–6 months time delay in the activity levels of two hemispheres. Furthermore, the wavelet analysis carried on the same data sets showed several known periodicities (e.g., 170–180 days, 2.1 year) in the north–south difference of sunspot area data. The temporal occurrence of these periods is also the same in all the three data sets. These results could help in understanding the underlying mechanism of north–south asymmetry of solar activity. 相似文献
158.
A. M. Finkelstein E. A. Skurikhina I. F. Surkis A. V. Ipatov I. A. Rakhimov S. G. Smolentsev 《Astronomy Letters》2008,34(1):59-68
Regular high-precision determinations of the Earth’s orientation parameters (EOPs) on the Quasar VLBI Network were begun in
August 2006. The observations are performed within the framework of two national programs: daily sessions at three observatories
of the Network to determine all five EOPs (the RU-E program) and 8-h sessions on the Zelenchukskaya-Badary and Svetloe-Badary
baselines to determine the Universal Time (the RU-U program). The observations from August 2006 through May 2007 are analyzed.
The rms deviations of the EOP values obtained in the RU-E program from the IERS C04 series are 1.1 mas for X
p and Y
p, 37 μs for UT1-UTC, and 0.7 and 0.6 mas for X
c and Y
c, respectively. These results closely match the prospective requirements of GLONASS. The rms deviations of the Universal Times
obtained in the RU-U program from the IERS C04 series are 146 μs. We consider the immediate prospects for improving the accuracy
of EOP determinations in daily sessions and for implementing the e-VLBI mode for an online determination of the Universal
Time.
Original Russian Text ? A.M. Finkelstein, E.A. Skurikhina, I.F. Surkis, A.V. Ipatov, I.A. Rakhimov, S.G. Smolentsev, 2008,
published in Pis’ma v Astronomicheskiĭ Zhurnal, 2008, Vol. 34, No. 1, pp. 66–76. 相似文献
159.
G. A. Tsirogiannis E. A. Perdios V. V. Markellos 《Celestial Mechanics and Dynamical Astronomy》2009,103(1):49-78
We present an improved grid search method for the global computation of periodic orbits in model problems of Dynamics, and
the classification of these orbits into families. The method concerns symmetric periodic orbits in problems of two degrees
of freedom with a conserved quantity, and is applied here to problems of Celestial Mechanics. It consists of two main phases;
a global sampling technique in a two-dimensional space of initial conditions and a data processing procedure for the classification
(clustering) of the periodic orbits into families characterized by continuous evolution of the orbital parameters of member
orbits. The method is tested by using it to recompute known results. It is then applied with advantage to the determination
of the branch families of the family f of retrograde satellites in Hill’s Lunar problem, and to the determination of irregular families of periodic orbits in a
perturbed Hill problem, a species of families which are difficult to find by continuation methods.
相似文献
160.
Giovanni Federico Gronchi 《Celestial Mechanics and Dynamical Astronomy》2009,103(4):301-326
Charlier’s theory (1910) provides a geometric interpretation of the occurrence of multiple solutions in Laplace’s method of
preliminary orbit determination, assuming geocentric observations. We introduce a generalization of this theory allowing to
take into account topocentric observations, that is observations made from the surface of the rotating Earth. The generalized
theory works for both Laplace’s and Gauss’ methods. We also provide a geometric definition of a curve that generalizes Charlier’s
limiting curve, separating regions with a different number of solutions. The results are generically different from Charlier’s:
they may change according to the value of a parameter that depends on the observations. 相似文献