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The reviewed Volumes of the AAA series record, summarize and index nearly 12 000 papers covering all aspects of astronomy and space sciences, published throughout the world during the first half of the year 1998. The AAA series is the most important source of information on progress in the scientific disciplines. They have become an indispensable source of information for scientists and students involved in the Universe research. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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The announcement last summer of the establishment of the U. S. Navy Space Command, and its subsequent activation at Dahlgren, Va., in October 1983, may have come as a surprise to some. This, however, was the latest of a series of actions taken by the Department of the Navy over the last several years to consolidate the Navy's space efforts. In fact, since the beginning of the Space Age, the Navy has been interested in space and involved in space-related activities. Its contributions in space science and technology have been significant. Driven by a realization that space assets are exceptionally well matched to its global mission, the Navy has become a major user of space. Primary areas of current activity include command, control, and communication and navigation and collection of environmental information. The Navy's operational use of space systems, the nature of the evolving Soviet threat (both air and space) directed in a large measure at U. S. naval targets, and the recent advances made in space technology, all argue for an increased level of Navy involvement in future Department of Defense space activities to secure Navy interests. As viewed by Navy decision-makers, this increased level of involvement will be selective in nature, emphasizing space research and development and operations that are considered vital to Navy interests.  相似文献   

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《中国航空学报》2015,28(2):0-0
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The Earth's auroral electrons produce copious non-thermal radio emissions of various types, including auroral kilometric radiation (AKR), whistler mode auroral hiss, mode conversion radiation such as auroral roar and MF-burst, and possibly HF/VHF emissions. In some cases, mechanisms have been identified and quantitatively described, whereby the energy of the auroral electrons is converted into electromagnetic radiation. In many other cases, the radiation mechanism, or the relative significance of several possible mechanisms, remains uncertain. This review covers fairly comprehensively experimental and theoretical research on types of auroral radiation other than AKR, concentrating on emissions with frequency higher than about 1kHz and treating only emissions which are unique to the auroral zone. The review covers both ground-based and in-situ observations. It covers a wide range of theoretical approaches, emphasizing those which at present appear most important for producing non-AKR auroral radiations.  相似文献   

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