排序方式: 共有54条查询结果,搜索用时 328 毫秒
31.
概况面对阿拉伯湾深蓝的海水和雄伟壮丽的Al Hajjar Mountains山景,这片绿洲可让您暂避尘世喧嚣。艾瓦迪悦榕庄是阿联酋首个提供全独立泳池别墅概念的沙漠度假村,拥有完备的设施,包括宽敞的全独立泳池别墅、源于亚洲的水疗spa设施、专属的自然保护区、私人海滩俱乐部及18洞锦标赛高尔夫球场。悦榕庄为城市居民提供一个独一无二的休闲体验,在度假村专属的自然保护区内,当地沙漠野生动物自由徜徉,另也备有精彩 相似文献
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Aja B. Pascual J.P. De La Fuente L. Detratti M Artal E. Mediavilla A. De Paco P Pradell i Cara L. 《IEEE transactions on aerospace and electronic systems》2005,41(4):1415-1430
This work describes the principle of operation, assembly and performance of one branch of the 44 GHz back end module (BEM) for the Planck low frequency instrument (LFI). This subsystem constitutes a fully representative branch of the qualification-model version (QM). It includes waveguide to microstrip transition, GaAs pseudomorphic high electron mobility transistor (PHEMT) low noise amplifiers (LNA), bandpass filter, square-law detector and dc amplifier. The fundamentals of the design of the RF part are described and all of the components have been tested individually before integration. Using single tone and wideband noise stimuli, the output voltage has been measured for several input powers, in order to obtain the sensitivity factor of the complete BEM. The effective bandwidth and the equivalent noise temperature have been calculated from the measurements, taking into account the frequency dependence on the noise source and the BEM. Finally, the low frequency output power spectrum has been obtained and a maximum 1/f knee frequency around 200 Hz has been measured with a 3 dB output signal video bandwidth above 50 KHz. 相似文献
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C La Tessa S Guetersloh L Heilbronn J Miller L Sihver C Zeitlin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(2):223-229
We have measured charged nuclear fragments produced by 1 GeV/nucleon 56Fe ions interacting with aluminium, polyethylene and lead. These materials are relevant for assessment of radiation risk for manned space flight. The data will be presented in a form suitable for comparison with models of nuclear fragmentation and transport, including linear energy transfer (LET) spectrum, fluence for iron and fragments, event-tack- and event-dose-averaged LET, total dose and iron contribution to dose. 相似文献
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A catalogue is presented of all the low-resolution IUE spectra of dwarf novae and nova-like stars that were recorded until the end of 1987. All spectra have been reduced, and are displayed, in a homogeneous way. In addition to details about these data, to the extent available, their position in the outburst light curves is given, physical information about each system, and a comprehensive list of references for published observations in all wavelength ranges.In collaboration with Janet A. Mattei, American Association of Variable Star Observers, 25 Birch Street, Cambridge, MA 02138-1205, U.S.A. 相似文献
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P. Ubertini A. Bazzano L. Boccaccini C. La Padula R.K. Manchanda M. Mastropietro R. Patriarca V.F. Polcaro G. Sabatino 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(4):87-90
In this paper the POKER-HXR81M hard X-Ray payload is described. The instrument, designed and built at the Istituto di Astrofisica Spaziale of Frascati, is a very large array of MultiWire Proportional Counters (MWPC) devoted to stratospheric observations of cosmic sources in the field of hard X-Ray Astronomy. The payload basically consists of four passively collimated MWPC's having a geometric sensitive area of 2,700 cm2 each with an efficiency higher than 10% in the operative range 15–200 KeV (80% at 60 KeV) with a square field of view of 5° × 5° FWHM. The overall spectral resolution is 13% at 60 KeV. The four MWPC's are filled with a very pure gas mixture of Xenon-Argon-Isobuthane at high pressure (3 bars).This experiment has been successfully flown during summer 1981 from the Milo balloon facility (Sicily, Italy). The performances of the payload and the preliminary results obtained during the 17 hours flight are discussed. 相似文献
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利用EDA技术在FPGA芯片上设计并实现一个简单的8位模型机,主要包括指令系统、运算器、控制器、存储器、时序产生器和总线等设计,在QuartusⅡ6.0集成环境下进行设计、编译和仿真,最后下载到SOPC/EDA实验平台上进行单元和系统测试,达到了设计要求。 相似文献
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We report the detection of three new hard X-Rays sources emitting in the range 15 – 150 KeV. Their observation was carried out by means of a balloon borne payload, consisting of two large area high spectral resolution Multiwire Spectroscopic Proportional Counters. 相似文献