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851.
The volume shift of 2000 cm3 from the lower to the upper part of the human body during weightlessness gave rise to theoretical and practical questions which are addressed in this communication. The analysis revealed that the mobilized fluid reduced the interstitial fluid of the lower extremities by 40%. Applying the current ideas in the field of interstitial tissue physiology to these problems, one must conclude that the fluid displacement can only be brought about by a change of the interstitial tissue compliance. Based on the observations made by the astronauts and on our working hypothesis, a method was proposed to follow the fluid migration and to measure the tissue compliance in man. Results are reported from experiments under terrestrial conditions. They show that the tissue compliance indeed can be modulated. Applying the method in space can eventually help to clarify several concepts in terrestrial physiology. 相似文献
852.
Norman F. Ness 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(8):171-176
Jupiter and Saturn are two of the more “exotic” planets in our solar system. The former possesses its own system with 15 satellites in orbit about the parent planet. Saturn has a uniquely well developed and distinctive ring system of particulate matter and also at least 11 satellites, including the largest one amongst all the planets, Titan, with a radius of 2900 km ± 100 km. In the decade of the 70's, the USA launched 4 unmanned spacecraft to probe these giant planets in-situ with a suite of highly advanced instrumentation. Four separate encounters have occurred at Jupiter: 1. Pioneer 10 in December 1973 2. Pioner 11 in December 1974 3. Voyager 1 in March 1979 4. Voyager 2 in July 1979 The characteristics of these trajectories is shown in Table I. Thus far, only a single encounter of Saturn has occurred, that by Pioneer 11 in September 1979. Future encounters of Saturn by Voyager spacecraft will occur in mid-November 1980 and late-August 1981. It is the purpose of this talk to summarize what is presently known about the magnetic fields of these planets and the characteristics of their magnetospheres, which are formed by interaction with the solar wind. 相似文献
853.
H E Ross 《Acta Astronautica》1981,8(9-10):1051-1058
It is often assumed that weight judgements depend primarily on the effort experienced in lifting an object against a 1-G force. Changes in effort and in other weight-cues certainly alter apparent heaviness; but there is a tendency towards mass-constancy when such changes are unrelated to mass. Under water or altered G, both the observer's body and other objects change their effective weight: the change in the former probably provides a cue to the latter. Mass-constancy increases with opportunity for adaptation to the change, leaving a negative aftereffect on return to normal circumstances. The discrimination of weight or mass also deteriorates with sudden changes in arm weight, just as it does with other types of maladaptation and with a reduction in sensory cues. The relative importance of arm weight and other factors has not been precisely measured, but experiments in prolonged spaceflight should help to elucidate the issue. 相似文献
854.
E.H. Lemke 《Acta Astronautica》1981,8(7):785-793
We examine the idea of accelerating a space ship, carrying a magnetic dipole moment, in a long inhomogeneous magnetic field. It is shown that it is technically possible to impart a mass of 10 tons a speed greater than the escape velocity of the solar system. We consider the flow of energy and give a rough calculation of the main parameters of the launching device. The device can be used continually and can decelerate a spacecraft with dipole moment equally well. 相似文献
855.
J.W. Warwick D.R. Evans J.H. Romig C.B. Sawyer 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(12):243-251
The Voyager Planetary Radio Astronomy Experiment detected strong 40 kHz to 850 kHz radio emissions from Uranus after closest approach and somewhat weaker emissions, but none above 100 kHz before closest approach, on the dayside of Uranus. The time variations of these emissions closely match Uranus' rotation, in a period of 17.24 h, and are evidently controlled by the strength and shape of its magnetic field. Throughout the entire encounter the polarization of the emission was approximately lefthand, corresponding to extraordinary mode. The emission associated with the nightside pole was a relatively smooth continuum (free of bursts) with a Gaussian-shaped rise and fall at low frequencies, 200 kHz for example, but a Gaussian with a central dip nearly to zero lasting a little less than two hours at frequencies above 400 kHz. Half a rotation later, when Voyager was near the magnetic equator of Uranus and farthest from the nightside dipole tip, the continuum emission was absent, but very strong, narrowband impulsive bursts appeared. Voyager successfully acquired one brief (24 seconds long) record of high time resolution radio observations in the range 500 to 700 kHz. This record, which was made near closest approach, shows a hierarchy of fast variations. Several days after closest approach, at the times of bowshock crossings outbound, the continuum emissions were modulated strongly in a manner suggestive of the presence of waves in the bowshock regions.
The instrument also recorded possible Uranian electrostatic discharges, vertex early arcs occurring in sequences of more than a dozen events with approximately ten-minute period, and, as early as several days before closest approach in the frequency range below 100 kHz, very intense isolated bursts lasting tens of minutes. 相似文献
856.
857.
Curves are presented showing the additional constant false-alarm rate (CFAR) loss which results when a "greatest of" logic is imple mented between the leading and lagging sets of reference cells. Thee analytical results for a square law detector and a Swerling case 1 fluctuating target are supplemented by simulation results for a nonfluctuating target, and envelope and logarithmic detector laws. 相似文献
858.
Performance data is presented for a sampled data delay-lock-loop incorporating a Kalman predictor. The jitter response due to noise and the deterministic response to aircraft maneuvers are investigated as a function of the Kalman model parameters. The predictor's transient response to step, ramp, and parabolic inputs and the number of iterations required for convergence for typical initialization errors are determined. It is shown how values for the model parameters may be chosen to obtain satisfactory noise, maneuver, and lock-up performance. 相似文献
859.
860.
F.B. McDonald Z. Fujii P. Ferrando B. Heber A. Raviart H. Kunow N. Lal R. Mller-Mellin G. Wibberenz R. McGuire C. Paizis 《Space Science Reviews》2001,97(1-4):321-325
The combination of Voyager 1 (77.9 AU, 34.4° N) and Voyager 2 (61.2 AU, 24.5° S) at moderate heliolatitudes in the distant heliosphere and Ulysses with its unique latitudinal surveys in the inner heliosphere along with IMP 8 and other satellites at 1 AU constitutes a
network of observatories that are ideally suited to study cosmic rays over the solar minimum of cycle 22 and the onset of
solar activity and the long term cosmic ray modulation of cycle 23. Through 2000.7 there have been three well-defined step
decreases in the cosmic ray intensity at 1 AU with the cumulative effect being in good agreement with the net decrease in
cycle 21 at a comparable time in the solar cycle. Over this period the intensity changes at Ulysses are similar to those at 1 AU. In the distant heliosphere the initial decreases appear to be smaller than those at 1 AU. However
the full effects of the interplanetary disturbances producing the most recent and largest step decrease in the inner heliosphere
have not yet reached V-2.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献