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21.
HD3196 = 13 Cet , HD30495 = 58 Eri and HD32918 have been detected as new late-type soft X-ray sources. HD32918 is a member of the FK Com class. 相似文献
22.
J.L. Culhane S. Pohjolainen L. van Driel-Gesztelyi P.K. Manoharan H.A. Elliott 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2007,40(12):1807-1814
Several methods for CME speed estimation are discussed. These include velocity derivation based on the frequency drifts observed in metric and decametric radio wave data using a range of coronal density models. Coronagraph height–time plots allow measurement of plane-of-sky and expansion speeds. These in turn can enable propagation speeds to be derived from a range of empirical relations. Simple geometric e.g., cone, models can provide propagation velocity estimates for suitable halo or partial halo events. Interplanetary scintillation observations allow speed estimates at large distances from the Sun detecting in particular the deceleration of the faster CMEs. Related interplanetary shocks and the arrival times and speeds of the associated magnetic clouds at Earth can also be considered. We discuss the application of some of these methods to the transit to Earth of a complex CME that originated earlier than 16:54 U.T. on 07-NOV-2004. The difficulties in making velocity estimates from radio observations, particularly under disturbed coronal conditions, are highlighted. 相似文献
23.
The THEMIS ESA Plasma Instrument and In-flight Calibration 总被引:3,自引:0,他引:3
J. P. McFadden C. W. Carlson D. Larson M. Ludlam R. Abiad B. Elliott P. Turin M. Marckwordt V. Angelopoulos 《Space Science Reviews》2008,141(1-4):277-302
The THEMIS plasma instrument is designed to measure the ion and electron distribution functions over the energy range from a few eV up to 30 keV for electrons and 25 keV for ions. The instrument consists of a pair of “top hat” electrostatic analyzers with common 180°×6° fields-of-view that sweep out 4π steradians each 3 s spin period. Particles are detected by microchannel plate detectors and binned into six distributions whose energy, angle, and time resolution depend upon instrument mode. On-board moments are calculated, and processing includes corrections for spacecraft potential. This paper focuses on the ground and in-flight calibrations of the 10 sensors on five spacecraft. Cross-calibrations were facilitated by having all the plasma measurements available with the same resolution and format, along with spacecraft potential and magnetic field measurements in the same data set. Lessons learned from this effort should be useful for future multi-satellite missions. 相似文献
24.
John R. Elliott 《Acta Astronautica》2011,68(3-4):435-440
Having dedicated prior research to identifying a range of methods for detecting the hierarchical layers of language, which also incorporates unsupervised learning toolkits and a Corpus that represents the entire ‘Human Chorus’, this paper outlines the concepts behind providing the last piece in the jigsaw. This particular piece, which ultimately will provide the ability to decipher meaning without an exhaustive crib or primer, poses the perplexing problem of dealing with the seemingly arbitrary nature of this linguistic ‘veneer’. Techniques that, if perfected, will also have a profound impact on developing a universal translator for everyday translation issues and cryptopalaeography. 相似文献
25.
Elliott D. Bloom 《Space Science Reviews》1996,75(1-2):109-125
A proposal for a new high energy gamma-ray space based detector using silicon strip technology is discussed. The detector is called GLAST for Gamma-ray Large Area Space Telescope. Results from Monte Carlo simulations are presented. The projected physics capabilities of GLAST are discussed in comparison to EGRET, currently in orbit on CGRO. Connections to the ground based gamma-ray observation program are explored. 相似文献
26.
Chris Elliott 《Space Policy》1997,13(4):315-322
Private users of space capability are used to buying a service, not a spacecraft. The supplier builds, launches and operates the spacecraft and the users only pay for the service that they receive. Publicly funded users could benefit from the same approach. Transferring responsibility for the success of the mission to a true prime contractor who is best able to manage technical and programme risks can lead to significant reductions in costs and timescales, but demands changes in attitudes by governments, users, industry and space agencies. 相似文献
27.
John Elliott 《Acta Astronautica》2011,68(3-4):418-424
The aim of HuLCC (the human language chorus corpus), is to provide a resource of sufficient size to facilitate inter-language analysis by incorporating languages from all the major language families: for the first time all aspects of typology will be incorporated within a single corpus, adhering to a consistent grammatical classification and granularity, which historically adopt a plethora of disparate schemes. An added feature will be the inclusion of a common text element, which will be translated across all languages, to provide a precise comparable thread for detailed linguistic analysis for translation strategies and a mechanism by which these mappings can be explicitly achieved. Methods developed to solve unambiguous mappings across these languages can then be adopted for any subsequent message authored by the SETI community. Initially, it is planned to provide at least 20,000 words for each chosen language, as this amount of text exceeds the point where randomly generated text can be disambiguated from natural language and is of sufficient size useful for message transmission [1] (Elliot, 2002). This paper details the design of this resource, which ultimately will be made available to SETI upon its completion, and discusses issues ‘core’ to any message construction. 相似文献
28.
The Mars Science Laboratory Engineering Cameras 总被引:1,自引:0,他引:1
J. Maki D. Thiessen A. Pourangi P. Kobzeff T. Litwin L. Scherr S. Elliott A. Dingizian M. Maimone 《Space Science Reviews》2012,170(1-4):77-93