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901.
Dusty pregalactic Population III objects may provide a mechanism for an effective thermalization of the star radiation. They may generate the observed microwave background and so the high cosmic photon entropy. Assuming a tepid universe a smaller primordial entropy contribution results in reasonable mass scales and amplification factors of pregalactic density fluctuations.  相似文献   
902.
A sequence of six well defined interplanetary structures (magnetic clouds) was identified in the solar wind and magnetic field measurements of Helios-1 from 29 June-01 July, 1980. (location 0.64–0.67 AU, C. Long. ~165°, C. Lat. ~5.8°). These structures were characterized by a large northward directed solar wind flow; by well defined directional discontinuities of mainly the ‘tangential-type’ at their beginnings and ends; by some increase in proton and by very pronounced increases in alpha particle number densities - each accompanied by sudden temperature decreases (or in one case by an increase); by some times an increase in magnetic field strength and by values of Nα/Np typical of the inner solar atmosphere. These structures are suggested to have been ejections from a succession (27–29 June, 1980) of Type II producing flares in Hale Region 16923 which coronagraph and X-ray (GOES) data indicate constituted a family of transient producing events. Only two interplanetary shocks were identified in the relevant Helios-1 records. It is suggested on the basis of observations of the directionality of certain of the flare related Type II bursts that some of these shocks could have been missed by the spacecraft. This implies that, in the absence of directional information, correlation of an observed interplanetary shock wave with a solar Type II burst may not always lead to a unique result.  相似文献   
903.
The implementation of satellite-based Doppler positioning systems frequently requires the recovery of transmitter position from a single pass of Doppler data. The least-squares approach to the problem yieds conjugate solutions on either side of the satellite subtrack. It is important to develop a procedure for choosing the proper solution which is correct in a high percentage of cases. A test for ambiguity resolution which is the most powerful in the sense that it maximizes the probability of a correct decision is derived. When systematic error sources are properly included in the least-squares reduction process to yield an optimal solution the test reduces to choosing the solution which provides the smaller valuation of the least-squares loss function. When systematic error sources are ignored in the least-squares reduction, the most powerful test is a quadratic form compasison with the weighting matrix of the quadratic form obtained by computing the pseudoinverse of a reduced-rank square matrix. A formula for computing the power of the most powerful test is provided. Numerical examples are included in which the power of the test is computed for situations that are relevant to the design of a satellite-aided search and rescue system.  相似文献   
904.
Measurements of the density and composition of the thermosphere between 150 and 500 km, which were obtained by the S3-1 satellite, have been compared with the Jacchia and MSIS models. The measurements of the densities of O, N2, N and Ar show some differences from the current models which should be considered during the preparation of the next CIRA model. The Ar measurements are particularly useful in examining the response of the neutral atmosphere to geomagnetic heating. These results are useful in establishing the appropriate lower boundary conditions for modeling of the thermosphere.  相似文献   
905.
Following a historical review of the first activities of GDR scientists in the fields of space research, especially on astronomical and geodetical satellite-observations and in atmospheric and magnetospheric research, the growing scientific and increasingly efficient technological and economic benefits of the cooperation of the Academy of sciences and other scientific and technological institutions of the GDR within the Intercosmos-programme are described. Especially, the experiences in connection with remote sensing, of the cooperation with countries as Cuba and the Peoples Republic of Vietnam and of the common USSR - GDR manned spaceflight are discussed under the viewpoint of the mutual interests of developing and developed countries in the fields of space science and technology.  相似文献   
906.
The multifunction display (MFD) developed for use as the primary cockpit display system on the US Air Force C-17A military air transport is described. The 6-in by 6-in color cathode ray tube (CRT) display features a self-contained 1750 processor and vector generator capable of processing MIL-STD-1553B aircraft data and raster video into any of 10 formats as selected by the pilot or copilot. The MFD can display stroke, raster, or hybrid formats in 16 colors. Raster images are driven by sensor inputs with an RS-170 or RS-343 interface. The CRT uses a taut mask delta gun design and provides the best available brightness and line-width performance. The display features small size, low weight, low power, standard interface, and adaptable software. Reconfigurability in the aircraft is enhanced by using four identical cockpit displays  相似文献   
907.
Diiminosuccinonitrile (DISN) has been investigated as a potential prebiotic phosphorylating agent. It is formed readily by the oxidation of diaminomaleonitrile (DAMN), a tetramer of HCN. DISN effects the cyclization of 3'-adenosine monophosphate to adenosine 2',3'-cyclic phosphace in up to 40% yield. The DISN-mediated phosphorylation of uridine to uridine mono-phosphate does not proceed efficiently in aqueous solution. The reaction of DISN and BrCN with uridine-5'-phosphate and uridine results in the formation of 2,2'-anhydronucleotides and 2,2'-anhydronucleosides respectively, and other reaction products resulting from an initial reaction at the 2'- and 3'-hydroxyl groups. The clay mineral catalysis of the cyclization of adenosine-3'-phosphate was investigated using homoionic montmorillonites.  相似文献   
908.
The model of beam-plasma discharge near the rocket following electron beam injection into the ionosphere is presented. The dependence of discharge plasma density on neutral atmosphere concentration and beam parameters is found. Radioemission and luminiscence intensities from discharge are estimated. The model is consistent with the data of ARAKS and “Zarnitsa-2” experiments.  相似文献   
909.
Environmental conditions on Mars are extremely hostile, and would be destructive to any organisms which might arrive there unprotected to-day. However, it is a biocompatible planet. Its unalterable astrophysical parameters would allow the maintenance of a much thicker, warmer carbon dioxide atmosphere than that which currently exists. Though very cold (averaging about -60 degrees C), highly oxidizing and desiccated, Mars may possess substantial quantities of the materials needed to support life--in particular, water and carbon dioxide. A general scenario for implanting life on Mars would include three main phases: (1) robotic and human exploration to determine whether sufficiently large and accessible volatile inventories are available; (2) planetary engineering designed to warm the planet, release liquid water and produce a thick carbon dioxide atmosphere; and (3) if no indigenous Martian organisms emerge as liquid water becomes available, a program of biological engineering designed to construct and implant pioneering microbial communities able to proliferate in the newly clement, though still anaerobic, Martian environment. The process of establishing an ecosystem, or biosphere, on a lifeless planet is best termed 'ecopoiesis.' This new word, derived from Greek, means 'the making of an abode for life.' It is by no means clear whether ecopoiesis on Mars is scientifically possible or technologically achievable. Thus we urge that it be one of the objectives of space research during the next century to assess the feasibility of ecopoiesis on Mars.  相似文献   
910.
The paper presents the results and discussion of VLF wave measurements carried out in the course of two rocket experiments on injection of a dense cesium ion beam into the ionosphere at the heights of 165–240 km. The injection was accompanied by enhancement of the broad-band noise by several orders of magnitude. The wave measurements in the frequency range of 1–11 kHz revealed two pronounced frequencies somewhat exceeding that of the lower-hybrid resonance oscillations in the background plasma and the cesium beam. The oscillations were modulated by frequencies close to the ion-cyclotron frequencies of the background plasma.  相似文献   
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