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641.
Pooja Dutt R.K. Sharma 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
A study of the evolution of the periodic and the quasi-periodic orbits near the Lagrangian point L2, which is located to the right of the smaller primary on the line joining the primaries and whose distance from the more massive primary is greater than the distance between the primaries, in the framework of restricted three-body problem for the Sun–Jupiter, Earth–Moon (relatively large mass ratio) and Saturn–Titan (relatively small mass ratio) systems is made. Two families of periodic orbits around the smaller primary are identified using the Poincaré surface of section method – family I (initially elliptical, gradually becomes egg-shaped with the increase in the Jacobi constant C and elongated towards the more massive primary) and family II (initially egg-shaped orbits elongated towards L2 and gradually becomes elliptical with the increase in C). The family I in the Sun–Jupiter and Saturn–Titan systems contains two separatrix caused by third-order and fourth-order resonances, while the Earth–Moon system has only one separatrix which is caused by third-order resonances. Also in the Sun–Jupiter and the Saturn–Titan systems, family I merge with family II, around Jacobian constant 3.0393 and 3.0163, respectively, while in the Earth–Moon system, family II evolves separately from two different branches. The two branches merge at C = 3.184515. In the Earth–Moon system, the family II contains a separatrix due to third-order resonances which is absent in the other two systems. 相似文献
642.
S. O. Karpenko N. V. Kupriyanova M. Yu. Ovchinnikov V. I. Penkov A. S. Selivanov O. E. Khromov 《Cosmic Research》2010,48(6):517-525
The results of designing the attitude control system of the first Russian nanosatellite TNS-0 no. 1 providing orientation of its longitudinal axis along the local geomagnetic field induction vector are presented. The system
consists of a permanent magnet and two sets of hysteresis rods. The magnetic and geometric parameters of the magnet and rods
are calculated. The influence of the permanent magnet field on the hysteresis rods and mutual influence of the rods in the
case of compact satellite packaging are analyzed. Examples of calculations of transient processes and steady-state angular
satellite motion are presented. 相似文献
643.
644.
V. M. Soldatkin A. A. Arkhipov V. A. Olaev A. A. Uglov 《Russian Aeronautics (Iz VUZ)》2012,55(2):184-191
We consider the function, the problems being solved and the construction principles for a starting system of warning the critical regimes for a single-rotor helicopter at parking, taxiing and maneuvering on the ground, takeoff and landing as well as at descending and hovering regimes. The structural-functional scheme and the algorithms of system channel warning are presented. 相似文献
645.
The problem of determining the “potential” number of integration steps by explicit difference schemes is solved within the framework of the prediction model for chemically non-equilibrium processes. 相似文献
646.
The paper discusses a method of designing the neural controller for two-channel control of a technical object by an example of the roll and yaw control depending on deviations, velocities and accelerations of their variation. 相似文献
647.
The methodology is proposed and the mathematical model is developed for the purpose of numerical simulation of the power circuit of the gas-hydraulic actuator with displacing power source for the gimbaled nozzle control. It provides the highest power efficiency factor of the actuator as a part of aircraft by means of pulling together the profiles of available and required power. 相似文献
648.
A problem of transverse bending of elastic isotropic parallelogram plates under the action of uniformly distributed load is considered. The plate sides are either pivoted or rigidly restrained. To determine the value of maximum plate deflection, it is proposed that an interpolation technique with respect to form factor be used; and as a geometrical argument, an inner-outer conformal radius ratio can be applied instead of the form factor. 相似文献
649.
Brian A. Tinsley 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
This paper outlines, and explores the uncertainties in, hypothesized connections between a series of processes that could explain two long-standing puzzles; those of (1) the observed winter storm vorticity responses to atmospheric energy inputs that change the ionosphere–earth current density, Jz, that appear to involve storm invigoration, and (2) changes in anti-cyclonic blocking and circulation that include the observed colder winters in Great Britain and western Europe at solar minima, and especially at extended solar minima. A working hypothesis for the mechanism responsible for (1) is that the flow of Jz through conductivity gradients, as in stratified cloud layers and fog, especially with sea-salt aerosol haze over the high latitude winter oceans, deposits electric changes on droplets and aerosol particles; most importantly on cloud condensation nuclei (CCN). These electric charges modulate scavenging of the particles in clouds and haze layers, increasing the concentration of small CCN and decreasing the concentration of large CCN. When further cloud formation occurs there is increased concentration of small droplets and decreased concentration of large ones, reducing coalescence and the production of rain. Thus updrafts carry more liquid water above the freezing level, and there the increased production of ice releases more latent heat and invigorates the updraft (the Rosenfeld mechanism), leading to increased vorticity. Here we explore the major uncertainties for the reality of the above chain of physical processes. A consequence of cumulative cyclonic vorticity increases is increases in downstream anti-cyclonic blocking. A further working hypothesis for (2) is that the invigoration may be large enough to contribute to the observed increases in blocking in winters at solar minima (high Jz) in the North Atlantic, that result in colder winters in the UK and northern Europe. 相似文献
650.
Direct measurements of the geomagnetic field have been made for more than 400 years, beginning with individual determinations of the angle between geographic and magnetic North. This was followed by the start of continuous time series of full vector measurements at geomagnetic observatories and the beginning of geomagnetic repeat stations surveys in the 19th century. In the second half of the 20th century, true global coverage with geomagnetic field measurements was accomplished by magnetometer payloads on low-Earth-orbiting satellites. This article describes the procedures and instruments for magnetic field measurements on ground and in space and covers geomagnetic observatories, repeat stations, automatic observatories, satellites and historic observations. Special emphasis is laid on the global network of geomagnetic observatories. 相似文献