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991.
E.M. Wescott H.C. Stenbaek-Nielsen T.J. Hallinan C.S. Deehr J.V. Olson J.G. Roederer R.D. Sydora 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(2):325-328
On 16 March 1980 a rocket launched from Poker Flat, Alaska, carried a new type of high-explosive barium shaped charge to 571 km, where detonation injected a thin disk of barium vapor with high velocity nearly perpendicular to the magnetic field. The purpose of the experiment, named “King Crab,” was to advance knowledge of the instabilities, waves, and optical and magnetic effects produced. The TV images of the injection are spectacular, revealing three major regimes of expanding material which showed early instabilities in the neutral gas. The most unusual effect of the injection is a peculiar rayed barium-ion structure lying in the injection plane and centered on a 5 km “black hole” surrounding the injection point. Preliminary computer simulations show a similar rayed structure development due to an electrostatic instability. 相似文献
992.
Keith O. Mason France A. Córdova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(9):109-117
Observations with the imaging X-ray detectors on the Einstein Observatory have led to a large increase in the number of low luminosity X-ray sources known to be associated with cataclysmic variable stars (CVs). The high sensitivity of the Einstein instrumentation has permitted study of their short timescale variability and spectra. The data are adding significantly to our knowledge of the accretion process in cataclysmic variables and forcing some revision in our ideas concerning the origin of the optical variability in these stars. 相似文献
993.
W.A. Delamere C.A. Hendrikson D.E. Schneible 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(4):39-47
Requirements on image stability are increasing, often at the same time that instrument external disturbances are increasing. Pointing large diameter optics from the shuttle bay is the prime current example of this situation. In order to achieve cost-effective advanced pointing systems in the face of these problems, a system approach must be taken that encompasses a realistic assessment of requirements, the best possible detector technology, and a broad look at space vehicles and pointing systems that are available. As an example, a rocket instrument for making measurements of the interstellar gas uses a standard pointing system to achieve a spectral resolution of 2 × 105. 相似文献
994.
GPS is an innovative technique for an electronic road pricing (ERP) system. By using GPS technology, ERP systems will be extremely efficient and cost-effective. This paper describes the next generation of ERP in Singapore and proposes a GPS based multisensor positioning system for ERP vehicles. Multisensor fusion algorithms are presented for the integration system. The integrated positioning system (IPS) developed in this paper makes it possible to realize GPS based ERP with a simple composition and low cost 相似文献
995.
The use of downlinked airspeed and magnetic heading data to enhance tracking in mode-S equipped air traffic control (ATC) systems is examined. A tracker performing satisfactorily during straight line flight as well as during steep maneuvers is discussed. The filter copes easily with longitudinally accelerating targets and is suitable for tracking low-velocity targets like helicopters in all phases of flight. The filter assumes that the target flies in a circular path from sample to sample, which results in nonlinear system equations. The filter is suitable for implementation in three-dimensional tracking systems, particularly on the vertical axis, where target velocities are usually small 相似文献
996.
A satellite-borne sensor can view a region at or above the Earth's surface. The size of this region depends on the satellite's altitude, the maximum range and scan angle of the sensor, the minimum above-the-horizon viewing angle required, the extent in altitude of the region to be viewed, and the maximum altitude of sensor obscuration by the atmosphere. Except for geosynchronous satellites this region moves relative to the Earth, so that constellations of satellites are generally necessary for continuous coverage. Satellite constellations which minimize the number of satellites required for continuous coverage are derived as a function of the angle subtended at the Earth's center by the coverage of a single satellite. This is done for single and triple continuous coverage of the entire Earth and of the polar regions extending to arbitrary latitude. Simple, cogent approximations for the configurations and numbers of satellites are found. Expressions which relate sensor capabilities and surveillance requirements to are presented. Examples are given to illustrate the use and accuracy of the results. 相似文献
997.
B. Schmieder P. Mein J.C. Vial E. Tandberg-Hanssen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(11):225-228
Simultaneous Hα (MSDP at Meudon) and C IV (UVSP aboard SMM) measurements of Active Region 2701 were made on October 2, 1980. Isodensity and velocity maps were derived for both lines and superposed. A good correlation was found between Hα and C IV velocities. A surge was observed for 10 minutes. The base was located in a bright point in CIV and Hα, and escaping matter followed the same channel (“absorbing” in Hα, “emitting” in C IV). The velocity along the surge was about 80 kms.-1 in Hα and 100 km s-1 in C IV. A loop appeared in C IV. We discuss the existing models and conclude that the vertical pressure gradient was capable of driving the surge. 相似文献
998.
P.M. Kintner M.C. Kelley 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(2):107-115
The Porcupine sounding rocket consisted of a central instrumented payload with 4 smaller payloads ejected in the radial direction. One of the smaller payloads contained a xenon ion gun which directed a 200eV Xe+ ion beam roughly perpendicular to the magnetic field. During the ion gun exercises a variety of plasma waves were observed by the δn/n experiment on the central spacecraft. For small separations betwen the ion gun and the plasma wave receivers, intense and very narrow band emissions were observed just above harmonics of the hydrogen gyrofrequency extending from n=1 to at least n=11 and perhaps to much higher harmonics. Additional structure at the helium gyrofrequency was also observed and the width of each spectral line was the order of the oxygen gyrofrequency. The fastest growing modes were at n=5 or 6. For larger separations between the ion gun and plasma wave receiver, band limited emissions were observed between the NO+ and O+ lower hybrid frequencies. The intense ion cyclotron harmonic waves observed for short separations are very similar to plasma waves observed at high altitudes in ion conics by the S3-3 satellite. In those examples, natural ion beams, which were nearly perpendicular to the magnetic field, produced plasma waves between harmonics of the hydrogen gyrofrequency and the most intense waves occurred between n=3 and n=7. Hence the ion beam experiment is directly applicable to understanding ion beams within the magnetosphere. 相似文献
999.
The mutual potential of 2 solid bodies is a function of the six parameters defining the relative position of these two bodies, it is not a function of only either 3 or 5 parameters as it is implicitly assumed in most studies.The sixth parameter, “the potential torsion” is related to the orientation of the two bodies around the axis of the two centers, its influence is small. An upper limit is given. 相似文献
1000.
C.T. Russell 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(8):3-20
Just as clearly as Mariner 10 established that Mercury has an intrinsic magnetic field, the Pioneer Venus orbiter has established that Venus has no significant intrinsic field. This is perhaps the opposite of what might be expected. Mercury, a small planet might be expected to cool rapidly and its internal dynamo to cease, while Venus, which is almost as large as the Earth, should not have lost much heat. On the contrary the source of energy of the Mercury dynamo appears to be extant whereas that of Venus appears to be extinct.The existence of a Martian magnetic field is controversial. No unambiguous signature of a Martian magnetic field has been reported. If the field on the nightside of Mars is of planetary rather than solar origin the Russian Mars spacecraft observations indicate the Martian dipole lies near the planetary equator rather than its pole. 相似文献