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1.
This book concerns the publication of the proceedings of an IAU Symposium held in Tokio in the summer of 1997. As implied by the title, it provides an overall review of our knowledge on all aspects of high-energy phenomena occurring in the universe obtained via the observations in X- and gamma-rays with orbiting satellites. It contains 44 invited (4 pages each) and 132 (2 pages each) contributed papers covering: Sun, stars, supernovae and their remnants, galaxies and their clusters, white dwarfs and neutron stars, black hole binaries, active galactic nuclei, gamma-ray bursts, large scale structure and hot intergalactic medium, and a chapter on future space programs in X- and gamma-ray astronomy. Many of the contributions have since appeared in the astronomical literature. The invited reviews, although very concise, are generally valuable in presenting the most relevant points of the various subjects. The book is for professional astronomers and may serve as a quick and very useful reference to becoming acquainted with the main developments in the field of high-energy astrophysics beginning of 1998. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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We see neutron stars principally by their radio and X-ray emission. Their appearance in these different bands depends on whether the emission comes from the surface or its magnetosphere. New phenomena continue to be found from neutron stars, which makes it an exciting and topical research area. This volume is a collection of the papers from a NATO Advanced Study Institute held in Italy in October 1996. Many, and for me the most interesting ones, are substantial reviews on topics such as Pulsar magnetic fields and glitches (M. Ruderman), Radio pulsar population properties (D. Lorimer), Gamma-ray emission from CGRO pulsars (G. Kanbach), Neutron stars and black holes in X-ray binaries (J. van Paradijs), Kilohertz quasi-periodic oscillations in low-mass X-ray binaries (M. van der Klis), Thermonuclear burning on rapidly accreting neutron stars (L. Bildsten), On the X-ray emission properties of rotation powered pulsars (W. Becker and J. Truemper). It will serve as a useful reference and source book for students in high energy astrophysics and related fields. The high price may deter its purchase by individuals, but it will be a good volume for a library needing recent coverage on neutron stars. It does not of course include the most recent developments on anomalous X-ray pulsars or magnetars. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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The editors have collected a comprehensive set of monographs that provide insight into the more recent history of bistatic radar design and implementation. This volume combines improved details of the environment along with novel system applications. Each chapter is authored by radar experts who had the vision and motivation to tackle a daunting development problem, and share their view of the successes and remaining implementation challenges. The book is divided into two parts: Bistatic/Multistatic Systems and Bistatic Clutter and Signal Processing. The book is an essential addition to the modern radar engineer's library.  相似文献   

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In the above-titled paper (see ibid., vol.26, no.4, July 1990), the authors presented a simple approach to suppressing Barker code compression sidelobes. It consists of approximating an inverse filter in a finite series of terms with unknown coefficients. The coefficients are then determined by a simplex solution to an appropriate linear programming problem. The commenter indicates the results are correct, but the steps taken contain two errors which, however, compensate for each other. The corrections are given by the authors in their reply.<>  相似文献   

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On 22 April, I visited the University of Missouri at Rolla where I lectured to the IEEE Student Branch on Navigation. I covered radio and inertial navigation with emphasis on GPS and cell phone positioning. The lecture was organized by Micah Weber, head of the Student Branch, and attended by about 25 students. My lecture followed their election of officers for the fall semester.  相似文献   

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The rapid rotation of the gas giant planets, Jupiter and Saturn, leads to the formation of magnetodisc regions in their magnetospheric environments. In these regions, relatively cold plasma is confined towards the equatorial regions, and the magnetic field generated by the azimuthal (ring) current adds to the planetary dipole, forming radially distended field lines near the equatorial plane. The ensuing force balance in the equatorial magnetodisc is strongly influenced by centrifugal stress and by the thermal pressure of hot ion populations, whose thermal energy is large compared to the magnitude of their centrifugal potential energy. The sources of plasma for the Jovian and Kronian magnetospheres are the respective satellites Io (a volcanic moon) and Enceladus (an icy moon). The plasma produced by these sources is globally transported outwards through the respective magnetosphere, and ultimately lost from the system. One of the most studied mechanisms for this transport is flux tube interchange, a plasma instability which displaces mass but does not displace magnetic flux—an important observational constraint for any transport process. Pressure anisotropy is likely to play a role in the loss of plasma from these magnetospheres. This is especially the case for the Jovian system, which can harbour strong parallel pressures at the equatorial segments of rotating, expanding flux tubes, leading to these regions becoming unstable, blowing open and releasing their plasma. Plasma mass loss is also associated with magnetic reconnection events in the magnetotail regions. In this overview, we summarise some important observational and theoretical concepts associated with the production and transport of plasma in giant planet magnetodiscs. We begin by considering aspects of force balance in these systems, and their coupling with the ionospheres of their parent planets. We then describe the role of the interaction between neutral and ionized species, and how it determines the rate at which plasma mass and momentum are added to the magnetodisc. Following this, we describe the observational properties of plasma injections, and the consequent implications for the nature of global plasma transport and magnetodisc stability. The theory of the flux tube interchange instability is reviewed, and the influences of gravity and magnetic curvature on the instability are described. The interaction between simulated interchange plasma structures and Saturn’s moon Titan is discussed, and its relationship to observed periodic phenomena at Saturn is described. Finally, the observation, generation and evolution of plasma waves associated with mass loading in the magnetodisc regions is reviewed.  相似文献   

7.
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   

8.
Over the last two decades the uninterrupted, high resolution observations of the Sun, from the excellent range of telescopes aboard many spacecraft complemented with observations from sophisticated ground-based telescopes have opened up a new world producing significantly more complete information on the physical conditions of the solar atmosphere than before. The interface between the lower solar atmosphere where energy is generated by subsurface convection and the corona comprises the chromosphere, which is dominated by jet-like, dynamic structures, called mottles when found in quiet regions, fibrils when found in active regions and spicules when observed at the solar limb. Recently, space observations with Hinode have led to the suggestion that there should exist two different types of spicules called Type?I and Type?II which have different properties. Ground-based observations in the Ca?ii H and K filtergrams reveal the existence of long, thin emission features called straws in observations close to the limb, and a class of short-lived events called rapid blue-shifted excursions characterized by large Doppler shifts that appear only in the blue wing of the Ca?ii infrared line. It has been suggested that the key to understanding how the solar plasma is accelerated and heated may well be found in the studies of these jet-like, dynamic events. However, while these structures are observed and studied for more than 130 years in the visible, but also in the UV and EUV emission lines and continua, there are still many questions to be answered. Thus, despite their importance and a multitude of observations performed and theoretical models proposed, questions regarding their origin, how they are formed, their physical parameters, their association with the underlying photospheric magnetic field, how they appear in the different spectral lines, and the interrelationship between structures observed in quiet and active regions on the disk and at the limb, as well as their role in global processes has not yet received definitive answers. In addition, how they affect the coronal heating and solar wind need to be further explored. In this review we present observations and physical properties of small-scale jet-like chromospheric events observed in active and quiet regions, on the disk and at the limb and discuss their interrelationship.  相似文献   

9.
The article's main theme is the ‘turbulence modelling’ used in present days' computational schemes. This modelling is an effort to account for the influence of turbulent motion on diffusion processes, and reflects our efforts to bridge what is generally recognized as the ‘closure gap’, i.e. to replace a needed phenomenological relation(s) with hypotheses of some kind. In this way one tries to remedy our lack of knowledge of turbulent motion. For that purpose a number of ideas and concepts over the past 60 years is mentioned and their incorporation in numerical analysis is discussed. The main emphasis is placed on the physical concepts and their consequences.  相似文献   

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A survey of current knowledge about Jupiter, Saturn, Uranus, Neptune, Pluto, and their satellites is presented. The best available numerical values are given for physical parameters, including orbital and body properties, atmospheric composition and structure, and photometric parameters. The more acceptable current theories of these bodies are outlined with thorough referencing offering access to the details. The survey attempts to cover the literature through May 1, 1972. Prepared Under Contract No. NAS7-100 National Aeronautics and Space Administration.  相似文献   

13.
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   

14.
This volume contains the proceedings of the NATO Advanced Study Institute on Polar Cap Boundary Phenomena held at Longyearbyen, Svalbard, Norway on June 4–13, 1997, which was the third NATO Workshop on magnetospheric boundary phenomena observable at high latitudes. Svalbard has a uniquely interesting location from observational point of view in that the dayside aurora can be observed there in the noon local time sector during the midwinter. The Norwegian groups working at Svalbard were the organisers of this third workshop as well as of the two earlier ones, but only this third one was held at Svalbard. It was attended by 86 space physicists from all over the world. The book contains 36 papers, of which the majority were presented as invited papers at the workshop, a few were contributed papers and the last paper in the volume gives a summary of the content of the workshop. As emphasized in both the Foreword and the Summary chapter of the book, the research field of the polar cap and its boundaries to other magnetospheric regions at high latitudes is one that has seen a fast development in the last ten years. This is to a great deal due to the research work done at Svalbard in combination with satellite measurements and theory development. The review in these proceedings provide also the non-specialist reader with good summaries of where different research questions stand at present. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

15.
《中国航空学报》2015,28(2):0-0
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推重比15一级发动机关键技术及分析   总被引:3,自引:0,他引:3       下载免费PDF全文
全面阐述和分析了推重比15一级涡扇发动机总体、风扇和压气机、燃烧室、涡轮、加力燃烧室、喷管等设计技术。  相似文献   

19.
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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