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841.
In this paper, we perform numerical simulation and experimental determination of the limiting resistance of the spacecraft design elements used when developing anti-meteorite protection of spacecraft as well as protection against space debris. One possible way to increase the efficiency of protective shields and satisfy the requirements of the mass characteristics of the latter is the use of mesh barriers. 相似文献
842.
We analyze the elastoplastic stress-strain state of an axisymmetrical parabolic type shell of revolution at the pole of which the concentrated force is applied. The shell is considered as a momentless one, and the properties of its material are schematized by the tensile diagram with linear hardening. The problem is solved in stresses, the corresponding equations are constructed, and the solution is given. 相似文献
843.
It is suggested that simultaneous monitoring of two flight actuator parameters, with proper analysis, could provide meaningful diagnostic information at very early stages of the developing failure 相似文献
844.
Coronal Mass Ejections (CMEs) are plasma eruptions from the solar atmosphere involving previously closed field regions which
are expelled into the interplanetary medium. Such regions, and the shocks which they may generate, have pronounced effects
on cosmic ray densities both locally and at some distance away. These energetic particle effects can often be used to identify
CMEs in the interplanetary medium, where they are usually called `ejecta'. When both the ejecta and shock effects are present
the resulting cosmic ray event is called a `classical, two-step' Forbush decrease. This paper will summarize the characteristics
of CMEs, their effects on particles and the present understanding of the mechanisms involved which cause the particle effects.
The role of CMEs in long term modulation will also be discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
845.
The concept, operation, and predicted performance of an RF tracking control system used to point the Pioneer F/G spacecraft at the Earth is described. This system employs a modified conical scanning technique called Conscan. The signal processor, the most interesting unit of the system, is described in detail to show that it approximates a maximum likelihood estimator. The dynamic behavior of the spacecraft and the stability analysis of the system are presented, demonstrating that the system performance is basically determined by the open-loop phase and amplitude errors introduced by the antenna, receiver, and signal processor. A detailed error budget shows that the phase and amplitude errors are small. Finally, closed-loop simulation and test data are presented to verify the error budget. 相似文献
846.
P.V.S. Rama Rao K. VenkateshD.S.V.V.D. Prasad K. Niranjan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The Indian sector encompasses the equatorial and low latitude regions where the ionosphere is highly dynamic and is characterized by the equatorial ionization anomaly (EIA) resulting in large latitudinal electron density gradients causing errors and uncertainties in the estimation of range delays in satellite based navigation systems. The diurnal and seasonal variations of standard deviations in the TEC data measured during the low sunspot period 2004–2005 at 10 different Indian stations located from equator to the anomaly crest region and beyond are examined and presented. The day-to-day variability in TEC is found to be lowest at the equatorial station and increases with latitude up to the crest region of EIA and decreases beyond. 相似文献
847.
AnalyticalredundancytechniquessuchasextendedKalmanfilter,componentstrackingfilterandsooncandetect,isolateandacommodatefailur... 相似文献
848.
Garmash V.R. Katsenelenbaum B.Z. Shaposhnikov S.S. Tioulpakov V.N. Vaganov R.B. 《Aerospace and Electronic Systems Magazine, IEEE》1998,13(10):39-41
Some wave beam peculiarities which usually are wasted are useful in wireless power transmission systems. These peculiarities-the focusing of the beam, the taper distribution of the radiating field, and the discontinuous antenna-are discussed 相似文献
849.
V A Shurshakov S L Huston V M Dachev TsPPetrov J V Ivanov YuVSemkova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1998,22(4):527-531
In March 1991 the CRRES spacecraft measured a new transient radiation belt resulting from a solar proton event and subsequent geomagnetic disturbance. The presence of this belt was also noted by dosimeter-radiometers aboard the Mir space station (approx. 400 km, 51 degrees orbit) and by particle telescopes on the NOAA-10 spacecraft (850 km, 98 degrees). This event provides a unique opportunity to compare particle flux and dose measurements made by different instruments in different orbits under changing conditions. We present here a comparison of the measurements made by the different detectors. We discuss the topology and dynamics of the transient radiation belt over a period of more than one year. 相似文献
850.
The existing technique of rating the external loads on a helicopter with skid type landing gear according to Airworthiness Standards [1] is analyzed and the results of comparing with design and experimental studies are presented. The main existing problems both in design simulation and the system of requirements to the conditions of rating the loads on the skid landing gear helicopter are identified. Also proposed are the techniques to increase safety of the helicopter emergency landing by refining the rating conditions of external loads at the design stage. 相似文献