An analytical representation of non-gyrotropic distributions and related space applications     

M.P. Leubner 《Planetary and Space Science》2003,51(12):723-729

Clear signature of non-gyrotropic energetic electron distributions was found by ISEE 1 and ISEE 2 spacecrafts just upstream of the Earth's bow shock and recently detected by in situ observations of the WIND plasma experiment. On the other hand, the appearance of non-gyrotropic ion velocity distributions is well established in the magnetotail providing evidence of magnetic reconnection processes. Motivated by these findings we introduce an analytical representation of non-Maxwellian/non-gyrotropic distribution functions, accurately fitting the characteristics of observations, where Maxwellians are recovered as special case of these highly general velocity space distributions. In particular, the analytical distribution function model can serve as basis of detailed wave-particle interaction analysis and of studies of the physical background of the evolution of both, non-gyrotropic electron and ion distributions, which is discussed for various space plasma environments.  相似文献   

Comet Hale-Bopp (C/1995 O1): UVSTAR-FUV Spectroscopy from the Space Shuttle     

Cristiano B. Cosmovici  Vojko Bratina  Gottfried Schwarz  Gianpaolo Tozzi  Michael J. Mumma  Roberto Stalio 《Astrophysics and Space Science》2006,301(1-4):135-143

We report here on unique post-perihelion (2.3 AU) measurements of Comet Hale-Bopp in the FUV-range (950–1250 Å) by means of the UVSTAR spectrometer from the space shuttle with the main purpose of searching for argon and other FUV emitters. New methods for separating the strong airglow emission at shuttle altitudes are here discussed in detail. Due to our low resolution (15 Å) and S/N ratio the possible rocket-borne detection of argon near perihelion (0.9 AU) could not be confirmed. New species as N₂ are suspected but difficult to separate from the strong airglow emission at shuttle altitudes. From the Lyα brightness (1.30± 0.08 kRy) a water production rate Q = 5.9 ± 0.4 × 10²⁹ molecules s^?1 could be derived and compared with other post-perihelion observations.  相似文献   

Ab initio infra-red spectra of iron-polycyclic aromatic hydrocarbon compounds: a model case     

《Planetary and Space Science》2002,50(9):871-876

C₁₀H₆-Fe⁺ complexes were observed by Fourier transform mass spectrometry by Marty et al. (Chem. Phys. Lett. 256 (1996) 669). In this article, we present the infra-red (IR) spectra of the two isomers calculated by ab initio methods of quantum chemistry. In the past, the same approach has predicted successfully unexpected features of the IR spectra of polycyclic aromatic hydrocarbon (PAH) cations which were confirmed by measurements in matrices (J. Phys. Chem. 98 (1994) 9187). The C₁₀H₆-Fe⁺ systems are models for larger PAHs-Fe⁺ complexes, which are believed to play a key rôle in space chemistry.  相似文献   

流动VLBI站氢原子钟的研制与性能测试     

张为群  林传富  于双林  张一平  王关忠  张健  杨佩红 《天文学报》2001,42(1):94-100

氢脉泽是射电天文所必需的频率标准.文中对为流动vLBI站研制的新一代氢脉泽的物理结构特点进行了讨论，包括对腔泡结构、磁屏蔽、原子束光学系统等.同时性能测试表明在80秒到1天之间频率稳定度优于1×10  相似文献   

The EVN-MarkIV VLBI Data Processor     

R. T. Schilizzi  W. Aldrich  B. Anderson  A. Bos  R. M. Campbell  J. Canaris  R. Cappallo  J. L. Casse  A. Cattani  J. Goodman  H. J. van Langevelde  A. Maccafferri  R. Millenaar  R. G. Noble  F. Olnon  S. M. Parsley  C. Phillips  S. V. Pogrebenko  D. Smythe  A. Szomoru  H. Verkouter  A. R. Whitney 《Experimental Astronomy》2001,12(1):49-67

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利用核对软件降低MARK IV格式磁带回放数据的误码率     

LU Chunmei 《中国科学院上海天文台年刊》2003,(1)

由于磁带回放的不稳定性及磁带与处理机的不匹配 ,导致由磁带导入硬盘的数据误码率很高 ,影响了送入处理机的数据可用率。结果显示 ,采用核对软件能将数据可用率提高一个数量级  相似文献   

Memorial landscapes: analytic questions and metaphors   总被引：1，自引：0，他引：1  

Owen J. Dwyer  Derek H. Alderman 《GeoJournal》2008,73(3):165-178

Over the past two decades, geographers have probed the intersection of collective memory and urban space. Their sustained interest in the subject reflects an understanding of the social condition of commemoration and the important role that space plays in the process and politics of collective memory. Along with other critical social scientists, geographers envision these public symbols as part of larger cultural landscapes that reflect and legitimate the normative social order. A review of the extant literature indicates that geographers scrutinize memorial landscapes through three conceptual lenses that may be understood via the metaphors of ‘text,’ ‘arena,’ and ‘performance.’ These metaphors are in turn mobilized through a series of analytic questions that serve to identify the interests served and denied by landscape ‘texts,’ the ‘arenas’ in which they are produced, and the ways in which they are enacted via ‘performance.’ This article’s synopsis of the subfield’s predominant metaphors and its attendant questions contributes to the ongoing cultural geographic project of articulating and implementing methods for interpreting landscapes as open-ended symbolic systems.

Derek H. AldermanEmail:

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气溶胶光学厚度的时空变化   总被引：2，自引：0，他引：2  

高飞  李铜基 《海洋技术学报》2003,22(3):15-19

在大气中气溶胶微粒是一种重要的大气微量成分。气溶胶光学厚度也是大气校正所需的重要大气参数，同时也是海洋水色卫星主要的数据产品。由于气溶胶光学厚度的时空变化较大，所以如何准确获取大气校正和卫星数据产品真实性检验所需的气溶胶光学厚度则是至关重要的。在简述气溶胶光学性质的基础上，并结合2002年6月HY—1南海实验数据来阐述现场气溶胶光学厚度的准确获取。  相似文献   

云南勐兴铅锌矿矿体空间特征及预测前景     

赵长江  高建国  王开林  丁秀芳 《云南地质》2008,27(4):496-501

借助ArcGIS软件的空间统计分析功能,对矿体主要参数进行分析,获得矿体空间特征。认为铅和锌品位具有明显的正相关,品位与厚度也属正相关。在此基础上对矿区找矿远景区进行初步圈定,为探矿工程的布置提供依据。  相似文献   

The development of radio astronomy at Hartebeesthoek     

George D. Nicolson 《Astrophysics and Space Science》1995,230(1-2):315-327

The development of radio astronomy at the Hartebeesthoek Radio Astronomy Observatory in South Africa is described. The Hartebeesthoek site was established originally by NASA as one of three Deep Space Stations equipped with 26-m parabolic reflector antennas. It was first used for radio astronomy by South Africa in terms of the NASA host nation agreement which allowed for its use at times when the facility was not needed for its primary purpose of tracking space probes. After NASA withdrew from South Africa in 1975, the South African Council for Scientific and Industrial Research took over the site and the 26-m parabolic reflector antenna, which NASA had abandoned in position, and established it as a national observatory. The development of the facility to the stage where it could support a variety of observing programmes such as continuum observations and mapping, spectroscopy and pulsar timing is described as well as the role played by the Observatory in global programmes of very long baseline interferometry.  相似文献