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51.
B. Aschenbach H. Bräuninger U. Briel W. Brinkmann H. Fink N. Heinecke H. Hippmann G. Kettenring G. Metzner A. Ondrusch E. Pfeffermann P. Predehl G. Reger K. -H. Stephan J. Trümper H. U. Zimmermann 《Space Science Reviews》1981,30(1-4):569-573
The primary scientific objective of the ROSAT mission is to perform the first all sky survey with an imaging X-ray telescope leading to an improvement in sensitivity by several orders of magnitude compared with previous surveys. Consequently a large number of new sources (> 105) will be discovered and located with an accuracy of 1 arcmin. After completion of the survey which will take about half a year the instrument will be used for detailed observations of selected targets.The X-ray telescope consists of a fourfold nested Wolter type I mirror system with 80 cm aperture and 240 cm focal length, and three focal plane detectors. In the baseline version these will be imaging proportional counters (0.1 – 2 keV) providing a field of view of 20 × 20. 相似文献
52.
The simplest version of the method of detecting the single molecular scattering field based on the polarization measurements of the twilight sky background by all-sky cameras has been considered. The method can be used during transitive twilight (with solar zenith angles of 94°–98°), when effective single scattering occurs in the upper stratosphere and lower mesosphere. The long-term measurements conducted using this method in the Moscow region and Apatity make it possible to determine the temperature of these atmospheric layers and estimate the contribution and properties of multiple scattering during the transitive twilight. 相似文献
53.
This remote assistance trial, performed within the framework of the manned space flight Altaïr, was carried out by CADMOS (CNES), with the cooperation of the Sub-directorate of CNES Operational Systems, Medes, LBM of Tours and Christol Consultants. It consisted of supplying the cosmonaut performing the Orthostatism experiment (echograph acquisition) on board the Mir station with realtime assistance by an expert (LBM of Tours) working from the ground on the CADMOS premises. The various steps of the approach followed during the preparation phase are described, as well as the technical means of communication used between the Mir station and CADMOS. 相似文献
54.
电火花加工计算机辅助工艺过程设计系统 总被引:1,自引:0,他引:1
介绍电火花计算机辅助工艺过程设计系统(CAPPS),用于为一个给定目标选择最佳操作。同时,还考虑了其它的会影响EDM加工过程的加工方法(如铣削等)。系统的输入信息是在已有的CAD信息的基础上产生的基于CAPP特征的工件描述。每个特征类对应于一个特定的一般工艺规程,并由系统对其进行评价,然后基于最低成本的原则,计算出最优工艺规程。同时还介绍了一种计算工时的通用方法。 相似文献
55.
Moatti JP Dousset N Moatti N Degre M Eche B Gasset G Tixador R 《Acta Astronautica》1995,36(8-12):527-533
The purpose of “Vitamin” experiment is to study the efficiency of protective substances on three biological acellular systems aqueous solutions exposed to cosmic radiation in space. The first system “LDL”is a low density lipoprotein. The second is “E2-TeBG complexe” in which estradiol (E2) is bound to its plasmatic carrier protein, testosterone-estradiol binding globulin (TeBG). The third is “pBR 322”, a plasmid. “Vitamin” experiment was accomodated in the Biopan which had been mounted on the outer surface of a Foton retrievable satellite. The experiment was exposed to space environment during 15 days. A stable temperature of about 20 °C was maintained throughout the flight. “Vitamin” experiment preliminary results are presented and discussed. 相似文献
56.
Malini Aggarwal H.P. Joshi K.N. Iyer Y.-S. Kwak J.J. Lee H. Chandra K.S. Cho 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The ionospheric total electron content (TEC) in the northern hemispheric equatorial ionization anomaly (EIA) crest region is investigated by using dual-frequency signals of the Global Positioning System (GPS) acquired from Rajkot (Geog. Lat. 22.29°N, Geog. Long. 70.74°E; Geom. Lat. 14.21°N, Geom. Long. 144.90°E), India. The day-to-day variability of EIA characteristics is examined during low solar activity period (F10.7∼83 sfu). It is found that the daily maximum TEC at EIA crest exhibits a day-to-day and strong semi-annual variability. The seasonal anomaly and equinoctial asymmetry in TEC at EIA is found non-existent and weaker, respectively. We found a moderate and positive correlation of daily magnitude of crest, Ic with daily F10.7 and EUV fluxes with a correlation coefficient of 0.43 and 0.33, respectively indicating an existence of a short-term relation between TEC at EIA and the solar radiation even during low solar activity period. The correlation of daily Ic with Dst index is also moderate (r = −0.35), whereas no correlation is found with the daily Kp index (r = 0.14) respectively. We found that the magnitude of EIA crest is moderately correlated with solar flux in all seasons except winter where it is weakly related (0.27). The magnitude of EIA crest is also found highly related with EEJ strength in spring (r = 0.69) and summer (r = 0.65) than autumn (0.5) and winter (r = 0.47), though EEJ is stronger in autumn than spring. 相似文献
57.
L.M. Mukhin D.F. Nenarokov N.V. Porschnev V.B. Bondarev B.G. Gelman G. Israel F. Raulin J. Runavot R. Thomas 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(12):329-335
SIGMA - 3 gas chromatograph on board VEGA 1 and 2 landing probes has been operated successfully in the 60 - 50 km altitude range, providing several in - situ chemical analysis of the gas and the aerosols of Venus cloud layers. Post flight calibration required to derive atmospheric abundancies from gas chromatograms were carried out using the SIGMA - 3 spare model. A Venus atmospheric aerosol simulation chamber was used in which sulfuric acid droplets were generated. Preliminary results of these calibration experiments indicate that the concentration of sulfuric acid in the upper part of the clouds ( 60 to 55 km) is about 1 mg/m3 and suggest that an additional constituant must be present in noticeable amount in the aerosols. From these experiments the mixing ratio upper limits of SO2 is 100 ppmV and of H2S and COS is few 10 ppmV. 相似文献
58.
Gawron T.E. Klembowski W. Pikielny J. Jakubiak A. Wojtkiewicz A. Czyz Z.H. Tuszynski M. Centkowski G. 《IEEE transactions on aerospace and electronic systems》1991,27(5):748-783
Polish radar research and development since 1953 is reviewed, covering the development and production of surveillance radars, height finders, tracking radars, air traffic control (ATC) radars and systems, and marine and Doppler radars. Some current work, including an L-band ATC radar for enroute control, a weather channel for primary surveillance radar, signal detection in non-Gaussian clutter, adaptive MTI filters and postdetection filtering, and a basic approach to radar polarimetry, is examined.<> 相似文献
59.
B. Valnicek V. Vanysek 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(12):137-141
A total of 3600 spectra of Comet Halley in the 275–710 nm were obtained on March, 8, 9, 10 and 11, 1986, from the VEGA 2 spacecraft. The emissions of OH, NH, CN, C3, CH, C2, NH2 and H2O+ are identified. From the OH intensity in the (0,0) band: 1.1 Megarayleigh at 5400 km from the nucleus, it can be inferred that the OH production rate was (1.4 ± 0.5)×1030 molecules s−1. The NH, C3, CH and NH2 bands became comparatively more intense at distances from the nucleus shorter than 3000km. At 06:40 U.T. when the instrument field of view was 6000×4500 km, two jets were observed. Spectra from the jets show significant differences with other spectra. Inside a jet NH, C3 and NH2 are comparatively more intense and the rotational distributions of OH, CN and C2 are strongly distorted. This shows that part of the observed emissions probably comes from radicals directly produced in the excited state during the initial process of photolysis of the parent molecules. 相似文献
60.
Johnson WH 《Acta Astronautica》1975,2(1-2):23-30
The early orbital flights, although undertaken with considerable confidence, involved some uncertainty because of the impossibility of simulating under terrestrial conditions all of the conditions encountered in space. However, space-flight achievements by both the American astronauts and Soviet cosmonauts have firmly established that man, if appropriately selected, trained, and protected by suitable life-support systems, can perform efficiently for long periods of time in the hostile environment of space. We know that the side effects of vestibular origin pose important problems in space exploration, and the neurophysiological effects of any extensive, rapid adaptation processes in subgravity states have enabled a better understanding of man's compensatory capabilities. With the successful establishment of orbiting research laboratories, an unparalleled opportunity exists that will undoubtedly enable better understanding of the role played by gravity in normal terrestrial activity, not only as it affects our vestibular physiology, but also as it may or may not concern other systems and at different organizational levels in the body. 相似文献