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191.
Xuexi Tie Guy Brasseur Peter Hess Martin Riese 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,24(12):1631-1636
Differences between the dynamical characteristics of the northern hemisphere (NH) and southern hemisphere (SH) stratosphere (e.g., the temperature, the strength of polar vortex, and the mean meridional circulation) produce hemispherically asymmetrical distributions of chemical species. In this paper, we use global models to briefly discuss various effects on chemical species caused by this asymmetrical distribution, especially on stratospheric ozone. The role of hemispheric asymmetries in chlorine and bromine loadings on mid- and high latitude ozone depletion is particularly discussed. 相似文献
192.
A 60 GHz phased array system for mm-wave frequency in 5 G is introduced and a 5 bit digitally controlled phase shifter in 40 nm CMOS technology is presented. In a phased array system,the signal to noise ratio(SNR)of the receiver is improved with the beaming forming function. Therefore,the communication data rate and distance are improved accordingly. The phase shifter is the key component for achieving the beam forming function,and its resolution and power consumption are also very critical. In the second half of this paper,an analysis of phase shifter is introduced,and a 60 GHz 5 bit digitally controlled phase shifter in 40 nm complementary metal oxide semiconductor(CMOS)technology is presented. In this presented phase shifter,a hybrid structure is implemented for its advantage on lower phase deviation while keeping comparable loss. Meanwhile,this digitally controlled phase shifter is much more compact than other works. For all 32 states,the minimum phase error is 1.5°,and the maximum phase error is 6.8°. The measured insertion loss is-20.9±1 d B including pad loss at 60 GHz and the return loss is more than 10 d B over 57—64 GHz. The total chip size is 0.24 mm2 with 0 m W DC power consumption. 相似文献
193.
Martin Wieser Leif Kalla Stas Barabash Tomas Hedqvist Stig Kemi Ola Widell Dominic Abplanalp Peter Wurz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The MEAP (Mars Environment Analogue Platform) mission was to fly a stratospheric balloon on a semicircular trajectory around the North Pole in summer 2008. The balloon platform carried the high-resolution neutral gas mass spectrometer P-BACE (Polar Balloon Atmospheric Composition Experiment) as scientific payload. MEAP/P-BACE is a joint project between the Esrange Space Center, Sweden, the University of Bern, Switzerland and the Swedish Institute of Space Physics (IRF), Kiruna, Sweden. Mission objectives were to validate the platform for future long duration flights around the North pole, to validate the P-BACE instrument design for planetary mission applications (conditions in the Earth stratosphere are similar to the conditions at the Mars surface), to study variation of the stratospheric composition during the flight and to gain experience in balloon based mass spectrometry. All objectives were fulfilled. 相似文献
194.
Peter R. Young Hui Tian Hardi Peter Robert J. Rutten Chris J. Nelson Zhenghua Huang Brigitte Schmieder Gregal J. M. Vissers Shin Toriumi Luc H. M. Rouppe van der Voort Maria S. Madjarska Sanja Danilovic Arkadiusz Berlicki L. P. Chitta Mark C. M. Cheung Chad Madsen Kevin P. Reardon Yukio Katsukawa Petr Heinzel 《Space Science Reviews》2018,214(8):120
The term “ultraviolet (UV) burst” is introduced to describe small, intense, transient brightenings in ultraviolet images of solar active regions. We inventorize their properties and provide a definition based on image sequences in transition-region lines. Coronal signatures are rare, and most bursts are associated with small-scale, canceling opposite-polarity fields in the photosphere that occur in emerging flux regions, moving magnetic features in sunspot moats, and sunspot light bridges. We also compare UV bursts with similar transition-region phenomena found previously in solar ultraviolet spectrometry and with similar phenomena at optical wavelengths, in particular Ellerman bombs. Akin to the latter, UV bursts are probably small-scale magnetic reconnection events occurring in the low atmosphere, at photospheric and/or chromospheric heights. Their intense emission in lines with optically thin formation gives unique diagnostic opportunities for studying the physics of magnetic reconnection in the low solar atmosphere. This paper is a review report from an International Space Science Institute team that met in 2016–2017. 相似文献
195.
The Lunar Orbiter Laser Altimeter Investigation on the Lunar Reconnaissance Orbiter Mission 总被引:3,自引:0,他引:3
David E. Smith Maria T. Zuber Glenn B. Jackson John F. Cavanaugh Gregory A. Neumann Haris Riris Xiaoli Sun Ronald S. Zellar Craig Coltharp Joseph Connelly Richard B. Katz Igor Kleyner Peter Liiva Adam Matuszeski Erwan M. Mazarico Jan F. McGarry Anne-Marie Novo-Gradac Melanie N. Ott Carlton Peters Luis A. Ramos-Izquierdo Lawrence Ramsey David D. Rowlands Stephen Schmidt V. Stanley Scott III George B. Shaw James C. Smith Joseph-Paul Swinski Mark H. Torrence Glenn Unger Anthony W. Yu Thomas W. Zagwodzki 《Space Science Reviews》2010,150(1-4):209-241
The Lunar Orbiter Laser Altimeter (LOLA) is an instrument on the payload of NASA’s Lunar Reconnaissance Orbiter spacecraft (LRO) (Chin et al., in Space Sci. Rev. 129:391–419, 2007). The instrument is designed to measure the shape of the Moon by measuring precisely the range from the spacecraft to the lunar surface, and incorporating precision orbit determination of LRO, referencing surface ranges to the Moon’s center of mass. LOLA has 5 beams and operates at 28 Hz, with a nominal accuracy of 10 cm. Its primary objective is to produce a global geodetic grid for the Moon to which all other observations can be precisely referenced. 相似文献