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281.
V. Ballu P. Bonnefond S. Calmant M.-N. Bouin B. Pelletier O. Laurain W.C. Crawford C. Baillard O. de Viron 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Measuring ground deformation underwater is essential for understanding Earth processes at many scales. One important example is subduction zones, which can generate devastating earthquakes and tsunamis, and where the most important deformation signal related to plate locking is usually offshore. We present an improved method for making offshore vertical deformation measurements, that involve combining tide gauge and altimetry data. We present data from two offshore sites located on either side of the plate interface at the New Hebrides subduction zone, where the Australian plate subducts beneath the North Fiji basin. These two sites have been equipped with pressure gauges since 1999, to extend an on-land GPS network across the plate interface. The pressure series measured at both sites show that Wusi Bank, located on the over-riding plate, subsides by 11 ± 4 mm/yr with respect to Sabine Bank, which is located on the down-going plate. By combining water depths derived from the on-bottom pressure data with sea surface heights derived from altimetry data, we determine variations of seafloor heights in a global reference frame. Using altimetry data from TOPEX/Poseidon, Jason-1, Jason-2 and Envisat missions, we find that the vertical motion at Sabine Bank is close to zero and that Wusi Bank subsides by at least 3 mm/yr and probably at most 11 mm/yr. 相似文献
282.
O. N. Naumov 《Russian Aeronautics (Iz VUZ)》2012,55(2):164-169
The results of the statistical analysis for the rotational motion of a light descent capsule under deployment of the orbital cable system are presented. At mathematical simulation a cable is considered to be a weightless inextensible mechanical linkage. The cable is deployed according to the predetermined law. The basic spacecraft is oriented along the local geovertical by means of its own stabilization system. The simulation is carried out by the statistical testing method. The motion characteristics being studied include: modulus of the capsule angular velocity and the nutation angle at the final point of the cable deployment. 相似文献
283.
284.
This paper discusses the results of early measurements of temperature and dust in the mesosphere on the basis of wide-field twilight sky polarimetry, which began in 2015 in Apatity (North of Russia, 67.6° N, 33.4° E) using the original entire-sky camera. These measurements have been performed for the first time beyond the Polar Circle in the winter and early spring period. The general polarization properties of the twilight sky and the procedure for identifying single scattering are described. The key results of the study include the Boltzmann temperature values at altitudes higher than 70 km and the conclusion on a weak effect of dust on scattering properties of the mesosphere during this period. 相似文献
285.
The spatial motion relative to the center of mass is considered for a capsule on an elastic tether, when it is unrolled from
a spacecraft by a special program. The spacecraft is in a circular orbit and oriented relative to the local vertical, which
is guaranteed by operation of its own stabilization system. Angular motion of the capsule relative to the tether direction
is studied, and the main factors influencing the stability of this motion are analyzed. An approximate quasi-linear mathematical
model of the capsule attitude motion is obtained, which allows one to estimate the influence of major disturbances of its
motion. The results of numerical simulations are presented for characteristic cases of the capsule motion. 相似文献
286.
Solar, geomagnetic and cosmic ray intensity changes, preceding the cyclone appearances around Mexico
J. Prez-Peraza S. Kavlakov V. Velasco A. Gallegos-Cruz E. Azpra-Romero O. Delgado-Delgado F. Villicaa-Cruz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,42(9):1601-1613
Recently it has been suggested that there exist specific changes in the cosmic ray intensity and some solar and geomagnetic parameters during the days, preceding the hurricane appearances over the North Atlantic Ocean. To understand better these phenomena, data for all hurricanes born not only over the Atlantic but also over the Pacific waters in the last 55 years that hit the Mexican borders were elaborated. As basic hurricane parameters the maximum rotational velocity and the estimated total energy were used. To avoid any interference all hurricanes, overlapping the preceding ones with more than 20 days were not included. Then the behavior of the cosmic ray (CR) intensity, the sunspot (SS) numbers, and the geomagnetic parameters (AP) and (KP) in 35 days prior and 20 days after the cyclone start were investigated. The CR, SS, AP and KP showed much more intensive disturbances in the periods preceding and following the hurricane appearance. For SS this disturbance gradually increase with the hurricane strength. A characteristic peak in the CR intensity appears before the hurricane start. But its place varies between 5 and 20 days before that start. Specific changes were observed in the SS. For major hurricanes they begins sometimes more than 20 days in advance. The AP and the KP show series of bursts, spread over the whole period of 30 preceding days. The obtained results from the performed correlational analysis are enough interesting to motivate a further statistical analysis with more precise techniques: in particular a common periodicity of 30 years found in the number of tropical storms landing into Mexico, the averaged rotational wind velocity and the ACE must be studied in connection with the solar Hale cycle. Using coherence wavelet spectral analysis we present a comparative study between one terrestrial and one cosmophysical phenomena that presumable influence hurricanes development: African dust outbreaks versus cosmic rays for all North Atlantic tropical cyclones. It is shown that the cosmophysical influence cannot be considered as a negligible effect. 相似文献
287.
A system for recording and analysis of flight information including the technical condition of a control object and the state of its controller’s health in real time aboard a flight vehicle and in ground-based air traffic control centers is described. 相似文献
288.
The characteristics of a master time and master-time dissemination subsystem for a collision avoidance system acceptable to the Air Transport Association of America are investigated. Selection of a time scale, a ground-station timing standard, and a synchronization technique are discussed. The conclusions are that a uniform time scale is ideal for the application, that a minimum of four cesium-beam standards are needed at each ground station, and that portable-clock synchronization is the only synchronization technique feasible at the present time. Considerations that suggest use of a nonuniform time scale are noted, and means of minimizing the adverse effects of the offsets necessitated by such an approach are described. Both single-master and weighted-average implementations of the time scale are discussed. 相似文献
289.
A novel guidance law designed specifically for a missile having forward and aft control systems is presented. For the derivation a linear quadratic differential games formulation of the end-game interception scenario is used. Conditions for achieving perfect intercept are given and new game spaces are presented. It is also shown that increasing the direct lift associated with the canard control allows intercepting targets with higher maneuvering capability, while for the tail control the effect is opposite. 相似文献
290.
The problem of the post-buckling behavior of the supported cylindrical panel under uniform axial compression is solved. The cylindrical supported panel is considered as a beam on the Winkler elastic foundation, the stiffness coefficient of which is calculated at the known value of buckling load. The criteria for post-buckling estimation are introduced, namely, vanishing of the determinant of the resolving system of equations and going to infinity of the deflection and strain energy in the implementation of post buckling. A good agreement of the post-buckling load obtained in this work with the experimental results is shown. 相似文献