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101.
102.
Larry W. Esposito Charles A. Barth Joshua E. Colwell George M. Lawrence William E. McClintock A. Ian F. Stewart H. Uwe Keller Axel Korth Hans Lauche Michel C. Festou Arthur L. Lane Candice J. Hansen Justin N. Maki Robert A. West Herbert Jahn Ralf Reulke Kerstin Warlich Donald E. Shemansky Yuk L. Yung 《Space Science Reviews》2004,115(1-4):299-361
The Cassini Ultraviolet Imaging Spectrograph (UVIS) is part of the remote sensing payload of the Cassini orbiter spacecraft. UVIS has two spectrographic channels that provide images and spectra covering the ranges from 56 to 118 nm and 110 to 190 nm. A third optical path with a solar blind CsI photocathode is used for high signal-to-noise-ratio stellar occultations by rings and atmospheres. A separate Hydrogen Deuterium Absorption Cell measures the relative abundance of deuterium and hydrogen from their Lyman-α emission. The UVIS science objectives include investigation of the chemistry, aerosols, clouds, and energy balance of the Titan and Saturn atmospheres; neutrals in the Saturn magnetosphere; the deuterium-to-hydrogen (D/H) ratio for Titan and Saturn; icy satellite surface properties; and the structure and evolution of Saturn’s rings.This revised version was published online in July 2005 with a corrected cover date. 相似文献
103.
质量偏心旋转机械碰摩故障特征及全息谱分析 总被引:3,自引:0,他引:3
本文针对仅考虑质量偏心的Jefcot转子碰摩的动力学方程,用二维全息谱理论研究了各阶谐波特性,得出碰摩的重要特征;分析了摩擦系数、转速对进动规律的影响,发现在摩擦系数较小时不平衡力引起的规则正进动起决定作用,较大时一定转速下将出现拟周期运动及失稳。 相似文献
104.
以实现冲压发动机等高压燃烧流场诊断为目标,采用可调谐半导体激光吸收光谱技术对带压的燃烧流场温度诊断进行初步研究。使用一种光谱适应的CT重构二维温度方法,以误差平方和和零均值归一化互相关作为评价指标分析CT-TDLAS的重构精度。搭建带压燃烧腔温度分布测量的实验系统,使用压力传感器和CCD相机记录带压点火燃烧过程变化;使用1335-1375nm的宽波段可调节半导体激光器对燃烧腔内带压点火燃烧过程进行了时间分辨的二维温度重建。实验结果表明:CT-TDLAS具有较高的重构精度;燃烧过程的压力变化趋势,火焰变化趋势及时间分辨二维温度分布变化趋势,三者保持一致;在带压条件下,CT-TDLAS可以实现高分辨率的时间分辨温度测量,反应定量的温度分布变化信息,为带压及进一步的高温高压燃烧流场的诊断提供帮助。 相似文献
105.
针对轻量化航天装备的可靠性服役对2195铝锂合金提出的高耐蚀性需求,采用环保型硫酸己二酸(50 g/L硫酸和10 g/L己二酸)溶液体系在2195铝锂合金表面制备阳极氧化膜,对所得的膜层通过沸水封闭、铬酸盐封闭、镍盐封闭和铈盐封闭4种封闭工艺进行后处理,并利用扫描电子显微镜、动电位极化曲线、电化学阻抗谱等方法对膜层表面的显微形貌和耐蚀性能进行表征。结果表明:相较于未封闭的阳极氧化膜,4种封闭工艺均提高了膜层的耐蚀性能,其中镍盐封闭后对基体的钝化效果最好,铬酸盐封闭次之,沸水封闭和铈盐封闭对膜层防腐性能提升有限。对电化学阻抗谱的进一步解析表明,4种膜层阻挡层电阻Rb均在105Ω·cm2数量级,膜层耐蚀能力主要来自于被水合及沉淀物充分填充的多孔层内部,相应的电阻Rp2的数值大小依次为镍盐封闭铬酸盐封闭沸水封闭≈铈盐封闭。 相似文献
106.
107.
Geeta Vichare Ankush Bhaskar Gauri Datar Anil Raghav K.U. Nair C. Selvaraj M. Ananthi A.K. Sinha M. Paranjape T. Gawade C.P. Anil Kumar C. Panneerselvam S. Sathishkumar S. Gurubaran 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(10):2555-2568
Recently, equatorial secondary cosmic ray observatory has been established at Equatorial Geophysical Research Laboratory (EGRL), Tirunelveli, (Geographic Coordinates: 8.71°N, 77.76°E), to study secondary cosmic rays (SCR) produced due to the interaction of primary cosmic rays with the Earth’s atmosphere. EGRL is a regional center of Indian Institute of Geomagnetism (IIG), located near the equator in the Southern part of India. Two NaI(Tl) scintillation detectors are installed inside the temperature controlled environment. One detector is cylindrical in shape of size 7.62?cm?×?7.62?cm and another one is rectangular cuboid of 10.16?cm?×?10.16?cm?×?40.64?cm size. Besides NaI(Tl) detectors, various other research facilities such as the Geomagnetic observatory, Medium Frequency Radar System, Digital Ionosonde, All-sky airglow imager, Atmospheric electricity laboratory to measure the near-Earth atmospheric electric fields are also available at EGRL. With the accessibility of multi- instrument facilities, the objective is set to understand the relationship between SCR and various atmospheric and ionospheric processes, during space weather and terrestrial events.For gamma-ray spectroscopy, it is important to test the performance of the NaI(Tl) scintillation detectors and to calibrate the gamma-ray spectrum in terms of energy. The present article describes the details of the experimental setup installed near the equator to study cosmic rays, along with the performance testing and calibration of the detectors under various conditions. A systematic shift in the gain is observed with varying temperature of the detector system. It is found that the detector’s response to the variations in the temperature is not just linear or non-linear type, but it depends on the history of the variation, indicating temperature hysteresis effects on NaI detector and PMT system. This signifies the importance of isothermal environment while studying SCR flux using NaI(Tl) detectors, especially for the experiments conducted during daytime such as solar eclipses etc. 相似文献
108.
A. Coradini M. C. De Sanctis F. Capaccioni G. Piccioni A. Romoli E. Suetta C. Giunti M. Barilli 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,33(12):2189-2194
The BepiColombo mission to Mercury is devoted to the thorough exploration of Mercury and its environment, with the aim to understand the processes of planetary formation and evolution in the hottest part of the protoplanetary nebula. This mission represents an unique opportunity for the European community to extend the understanding of the Solar Nebula evolution from its outer edge – ideally represented by comets – to its inner and warmer edge. Obviously this exploration asks for a detailed knowledge of the main constituents of the matter present in the different Solar System areas. Spectroscopy is a powerful tool to acquire this knowledge. We have participated with a large consortium of European researchers to the development of the Rosetta imaging spectrometer. We propose here to use our experience to develop a newly designed spectrometer to investigate the mineralogical composition of the Mercurial surface. Given the particular thermodynamical situation of the Mercurial surface, we have developed a concept that combines a medium IR low spectral resolution imager with a moderate spectral resolution NIR point spectrometer. The main goal of METHIS is to provide the mineralogical characterisation of the surface with sufficient spectral resolution in a scientifically diagnostic spectral range. 相似文献
109.
The volatile species released in the coma are an important clue to the composition of the cometary nucleus ices. Their identification
and the measurement of their abundances is possible by remote sensing. Considerable progress has been made recently using
radio and infrared spectroscopy, especially with the observations of the two exceptional comets C/1996 B2 (Hyakutake) and
C/1995 O1 (Hale-Bopp).) 24 molecules likely to be parent molecules outgassed from the nucleus have now been identified. Significant
upper limits exist for many other species, and the presence of unidentified lines suggests that further species are to be
identified. In addition, isotopic varieties have been observed for hydrogen, carbon, nitrogen and sulphur. We will review
these results with a special emphasis on the reliability of the identifications and of the molecular production rate determinations.
A critical point is to assess whether a given species is a genuine parent molecule outgassed from nuclear ices, or is a secondary
product coming from grains or from gas-phase photochemistry. Ground-based spectral imaging, such as radio interferometry,
may help resolving this problem.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
110.
用SIMOX(Separationby Implanted Oxygen,即氧注入隔离)技术制备SOI-CMOS用的SOI(Silicon OnInsu lator,即绝缘体上长单晶硅膜)样品;对SOI样品红外吸收光谱的分析,从而计算了SOI结构材料中SiO2埋层的厚度;测试样品不同点的红外吸收光谱,可考察样品SiO2埋层厚度的不均匀性,据此,并可分析与之相关的SOI样品的质量参数.这种分析方法,是一种无损的检测手段,具有实用价值. 相似文献