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Aprajita Verma Vassilis Charmandaris Ulrich Klaas Dieter Lutz Martin Haas 《Space Science Reviews》2005,119(1-4):355-407
Some of the most ‘active’ galaxies in the Universe are obscured by large quantities of dust and emit a substantial fraction
of their bolometric luminosity in the infrared. Observations of these infrared luminous galaxies with the Infrared Space Observatory
(ISO) have provided a relatively unabsorbed view to the sources fuelling this active emission. The improved sensitivity, spatial
resolution and spectroscopic capability of ISO over its predecessor Infrared Astronomical Satellite (IRAS) of enabled significant
advances in the understanding of the infrared properties of active galaxies. ISO surveyed a wide range of active galaxies
which, in the context of this review, includes those powered by intense bursts of star formation as well as those containing
a dominant active galactic nucleus (AGN). Mid-infrared imaging resolved for the first time the dust enshrouded nuclei in many
nearby galaxies, while a new era in infrared spectroscopy was opened by probing a wealth of atomic, ionic and molecular lines
as well as broad band features in the mid- and far-infrared. This was particularly useful, since it resulted in the understanding
of the power production, excitation and fuelling mechanisms in the nuclei of active galaxies including the intriguing but
so far elusive ultraluminous infrared galaxies. Detailed studies of various classes of AGN and quasars greatly improved our
understanding of the unification scenario. Far-infrared imaging and photometry revealed the presence of a new very cold dust
component in galaxies and furthered our knowledge of the far-infrared properties of faint starbursts, ULIGs and quasars. We
summarise almost nine years of key results based on ISO data spanning the full range of luminosity and type of active galaxies. 相似文献
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C. Taricco N. Bhandari P. Colombetti N. Verma 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(2):275-279
Measurements of 44Ti activity in meteorites show that the galactic cosmic ray (GCR) intensity has been declining in the interplanetary space during the past three centuries and has a component of cyclic variation, with periodicity of about 87 years [Taricco, C., Bhandari, N., Cane, D., et al. Galactic cosmic ray flux decline and periodicities in the interplanetary space during the last 3 centuries revealed by 44Ti in meteorites. J. Geophys. Res. 111, A08102, 2006.]. In order to verify these results, we have measured 44Ti activity in Allegan meteorite which fell in 1899 and in some other meteorites with better precision. The measurements confirm low cosmic ray flux and consequently high solar activity near the middle of 19th century. 相似文献
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M.K. Sharma Monika Sharma U.P. Verma Suresh Chandra 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Though H2CO, H2CS, H2CCC, H2CCCC, H2CCO have been identified in cool interstellar molecular clouds, identification of H2CC is still awaited. To analyze its spectrum, collisional rate coefficients are required. We have calculated collisional rate coefficients for rotational transitions between 23 levels of ortho and para H2CC for kinetic temperatures 10, 20, 30, 40, and 50 K. The scattering problem is analyzed using the computer code MOLSCAT where the colliding partner is He atom. The interaction between H2CC and He has been calculated with GAUSSIAN 2003. For the interaction potential obtained with GAUSSIAN 2003, MOLSCAT is used to derive the parameters q(L,M,M′|E) as a function of energy E of the colliding partner. After averaging the parameters q(L,M,M′|E) over a Maxwellian distribution, the parameters Q(L,M,M′|T) as a function of the kinetic temperature T in the cloud are obtained. Finally, the collisional rate coefficients have been calculated. 相似文献
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Buede D. Farr J. Powell R. Verma D. 《Aerospace and Electronic Systems Magazine, IEEE》2003,18(10):3-8
An air traffic management system (ATMS) is a network-centric system being used to manage another network-centric system, namely, an air transportation system. We are developing a design language for network-centric systems and design guidelines for the development system of engineers and domain specialists involved in designing and integrating systems. Note: this development system with today's technology is also a network-centric system. An outline of the design language under construction and the design guidelines being studied is provided. Specifically we discuss ATMS mission objectives (e.g., average yearly throughput of people and freight for a high demand scenario); ATMS sample usage scenarios (e.g., ATMS reroutes air traffic in time and space in reaction to major weather deviation along the northeast coast); and system objectives for an ATMS (e.g., timelines of a specific high volume of messages from aircraft, weather sensors, and airports). We lay out some key design decisions associated with both the development system of engineers and domain specialists and the operational ATMS. Examples of key design decisions for the engineering system are: 1) appropriate partitioning of functional/physical architectures of the engineering system; 2) appropriate degree to telecollaboration and collaboration among design/integration groups; 3) appropriate incremental delivery packages for an incremental delivery schedule of ATMS elements; and 4) appropriate levels and thrusts of the risk management program. Examples of key design decisions for the operational ATMS are: 1) throughput and security trades of the ATMS and 2) throughput and resiliency to weather changes. Finally, we relate network-centric architecture issues to both of the above sets of design decisions. 相似文献
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This paper presents a design concept for an azimuth and an elevation antenna suitable for the light weight Portable Approach Landing System (PALS). The proposed design complies with the requirements of the International Civil Aviation Organization (ICAO) Annex 10. Based on a proven technology, the proposed design offers a low risk and a cost effective approach 相似文献
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In the paper we have investigated the periodicity of high speed solar wind (HSSW) streams using the technique of power spectrum
analysis. The data for HSSW streams has been taken from the papers by Lindblad and Lundstedt (1981, 1983) and Lindblad et al. (1989) The power spectrum analysis of the daily HSSW streams events for the period 1964–1975 (solar cycle 20) shows peaks
of 14, 7, 2.9 and 2.6 days, and daily HSSW events for the period 1976–1982 (solar cycle 21) shows peaks of 15.4, 7, 2.9 and
2.6 days. The HSSW events for period 1964–1982 (solar cycles 20-21) shows peaks of 15.4, 7, 3.7, 2.9 and 2.6 days. The common
periods from above study are 7, 2.9 and 2.6 days. The 2.9, 2.6 days and other periods are folding frequency. The 7 days periodicity
is close to the
th of solar rotation which may be the time for energy build up for coronal holes to produce HSSW streams.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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