排序方式: 共有98条查询结果,搜索用时 15 毫秒
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危地马拉位于中美洲地峡的西北部,东临加勒比海及洪都拉斯,东南连接萨尔瓦多,南濒太平洋,西北部与墨西哥交界,它的国名(Guatemala)由古代玛雅地名"Quauhtemellan"的译音演变而来,意为"森林的大地"作为除墨西哥外中美洲人口最多的国家,危地马拉还是玛雅古文明的发祥地,同时也是火山最多的国家——共有37座火山,其中3座是活火山危地马拉早在1838年就已经独立,但直到1996年各党派签定"和平协议"后政局才趋于稳定。 相似文献
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ZHANG Juna b HU Ziyinga ZHANG Taoa b aSchool of Electronics Information Engineering Beihang University Beijing China bNational Key Laboratory of CNS/ATM China 《中国航空学报》2011,24(2):202-209
This paper presents a novel approach for checking route oscillation of border gateway protocol(BGP) quickly,by which the privacy of routing policies of autonomous system(AS) can be respected.Firstly,route update chain tag(RUCT) is constructed to track the forwarding of update report,and local routing library is made to record the changing history of update report.Then route oscillation can be identified by analyzing correlative state of RUCT and local routing library.The characteristic of this approach is that an arbitrary AS can check route oscillation alone only by sharing its network ID,which greatly respects the pri-vacy of routing policies for each AS.This paper shows that both looping in RUCT and consecutive positive-negative report in local record are sufficient conditions for route oscillation.Comparative experiments demonstrate the availability and efficiency of the proposed approach. 相似文献
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Alan M. Levine Hale Bradt Edward H. Morgan Ron Remillard The MIT/GSFC ASM Team 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2970-2975
Selected results from the Rossi X-ray Timing Explorer</i> All-Sky Monitor are presented to illustrate the phenomenology of the light curves. The sensitivity to periodic intensity variations is indicated by the folded light curve of AM Her. The gray line between transient and persistent sources is emphasized. Light curves of a range of systems comprising black holes or neutron stars and low and high mass companion stars show that the behavior of these systems is often, but not always, characteristic. 相似文献
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V M Petrov V S Mahkmtov N A Panova V A Shurshakov J V Dachev TsPSemkova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):645-650
Flux and dose rate dynamics of solar cosmic rays were measured by the Lyulin dosimeter during the events 19 October 1989 and 23 March 1991. The maximum dose rate registered was 0.4, 0.12 and 0.01 cGy/hour, respectively. Based on the latitude distribution of particle flux a power law form for the energy spectra of solar protons in the anisotropic phase of the events on 19 October 1989 and 23 March 1991 was determined. It was obtained that after the development of geomagnetic storm protons with energies more than 1 GeV were registered. 相似文献
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N S Manukovsky V S Kovalev I G Rygalov VYeZolotukhin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(10):1827-1832
An experimental model of matter turnover in the biotic cycle: plants (plant biomass) --> mushrooms (residual substrate + mushroom fruit bodies) --> worms (biohumus) --> microorganisms (soillike substrate) --> plants is presented. The initial mass of soillike substrate was produced from wheat plants grown in a hydroponic system. Three cycles of matter turnover in the biotic cycle were carried out. Grain productivity on soillike substrate was 21.87 g/m2 day. The results obtained were used for designing a CES containing man, plants, soillike substrate, bioregeneration module and aquaculture. It was shown, that the circulating dry mass of the CES is 756 kg. The main part (88%) of the circulating mass accumulates in the soillike substrate and bioregeneration module. 相似文献
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A. Nakajima
M. Abe
Y. Nishio
H. Yahagi
《Acta Astronautica》1991,25(12):765-773This paper describes the results of the in-orbit performance testing of deployable and retractable umbrella and boom systems, which will be used as important subsystems of Boomerang/Tether satellites. The umbrella is one of the possible candidates of the aerodynamic braking system for boomerang satellite and the boom is also one of the possible candidates of relative position adjusting mechanism between center of mass and aerodynamic force center of the boomerang satellite and initial release/final recovery mechanism of the tethered satellite. For this technology verification, a small and inexpensive satellite, named DEBUT (Deployable Boom and Umbrella Test satellite), was developed in a short period of 1.5 years elapsing from the start of the detailed design until the launch of the mission. The lithium dry cell batteries were used as the primary power and functioned normally during 10 days mission lifetime. 相似文献