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51.
J.H. Telting G. Avila L. Buchhave S. Frandsen D. Gandolfi B. Lindberg H.C. Stempels the NOT staff S. Prins 《Astronomische Nachrichten》2014,335(1):41-45
FIES is a cross‐dispersed high‐resolution echelle spectrograph at the 2.56 m Nordic Optical Telescope (NOT), and was optimised for throughput and stability in 2006. The major 2006 upgrade involved the relocation of FIES to a stable environment and development of a fiber bundle that offers 3 different resolution modes, and made FIES an attractive tool for the user community of the NOT. Radial‐velocity stability is achieved through double‐chamber active temperature control. A dedicated data reduction tool, FIEStool, was developed. As a result of these upgrades, FIES is now one of the work‐horse instruments at the NOT. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
52.
We describe a forward-fitting method that has been developed to reconstruct hard X-ray images of solar flares from the Ramaty
High-Energy Solar Spectroscopic Imager (RHESSI), a Fourier imager with rotation-modulated collimators that was launched on
5 February 2002. The forward-fitting method is based on geometric models that represent a spatial map by a superposition of
multiple source structures, which are quantified by circular gaussians (4 parameters per source), elliptical gaussians (6
parameters), or curved ellipticals (7 parameters), designed to characterize real solar flare hard X-ray maps with a minimum
number of geometric elements. We describe and demonstrate the use of the forward-fitting algorithm. We perform some 500 simulations
of rotation-modulated time profiles of the 9 RHESSI detectors, based on single and multiple source structures, and perform
their image reconstruction. We quantify the fidelity of the image reconstruction, as function of photon statistics, and the
accuracy of retrieved source positions, widths, and fluxes. We outline applications for which the forward-fitting code is
most suitable, such as measurements of the energy-dependent altitude of energy loss near the limb, or footpoint separation
during flares.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022469811115 相似文献
53.
黑柱石是一种少见的含钙铁硅酸盐矿物。通过富含黑柱石的青海省双庆铁矿区与仅含少量黑柱石的福建省马坑铁矿区矿床地质特征的对比,认为矿床中黑柱石的产生与中基性火成岩的参与有关;黑柱石的解体与硼的参与有关。 相似文献
54.
M.A. Janssen R.D. Lorenz F. Paganelli R.L. Kirk S.D. Wall Y. Anderson P. Callahan G.A. Hamilton L. Roth A. Le Gall the Cassini Radar Team 《Icarus》2009,200(1):222-239
The first comprehensive calibration and mapping of the thermal microwave emission from Titan's surface is reported based on radiometric data obtained at 2.2-cm wavelength by the passive radiometer included in the Cassini Radar instrument. The data reported were accumulated from 69 separate observational segments in Titan passes from Ta (October 2004) through T30 (May 2007) and include emission from 94% of Titan's surface. They are diverse in the key observing parameters of emission angle, polarization, and spatial resolution, and their reduction into calibrated global mosaic maps involved several steps. Analysis of the polarimetry obtained at low to moderate resolution (50+ km) enabled integration of the radiometry into a single mosaic of the equivalent brightness temperature at normal incidence with a relative precision of about 1 K. The Huygens probe measurement of Titan's surface temperature and radiometry obtained on Titan's dune fields allowed us to infer an absolute calibration estimated to be accurate to a level approaching 1 K. The results provide evidence for a surface that is complex and varied on large scales. The radiometry primarily constrains physical properties of the surface, where we see strong evidence for subsurface (volume) scattering as a dominant mechanism that determines the emissivity, with the possibility of a fluffy or graded-density surface layer in many regions. The results are consistent with, but not necessarily definitive of a surface composition resulting from the slow deposition and processing of organic compounds from the atmosphere. 相似文献
55.
The Swedish Deep Drilling Program (SDDP) has been initiated to study fundamental problems of the dynamic Earth system, its natural history and evolution. Many key scientific questions can be addressed through in situ investigations only, requiring deep continental drilling. Some are unique to Scandinavia, most are of international interest and significance. At present, five core projects ( Fig. 1 ) with international teams are integrating scientific problems with societal and industrial applications. If SDDP succeeds to attract the funding required, Sweden will have a number of world‐class boreholes at key locations by 2020.
56.
The Classification and Model of Coalbed Methane Reservoirs 总被引:8,自引:0,他引:8
SU Xianbo LIN Xiaoying SONG Yan ZHAO Mengjun Henan University of the Sciences Jiaozuo Henan Research Institute of Petroleum Exploration Development PetroChin Beijing 《《地质学报》英文版》2004,78(3):662-666
Coalbed methane has been explored in many basins worldwide for 30 years, and has been developed commercially in some of the basins. Many researchers have described the characteristics of coalbed methane geology and technology systematically. According to these investigations, a coalbed methane reservoir can be defined: "a coal seam that contains some coalbed methane and is isolated from other fluid units is called a coalbed methane reservoir". On the basis of anatomization, analysis, and comparison of the typical coalbed methane reservoirs, coalbed methane reservoirs can be divided into two classes: the hydrodynamic sealing coalbed methane reservoirs and the self-sealing coalbed methane reservoirs. The former can be further divided into two sub-classes: the hydrodynamic capping coalbed methane reservoirs, which can be divided into five types and the hydrodynamic driving coalbed methane reservoirs, which can be divided into three types. The latter can be divided into three types. Currently, hydrodynamic s 相似文献
57.
We review results of Suzaku observations of the intracluster medium of clusters of galaxies whose O, Mg, Si, S and Fe abundances have been measured with good accuracy due to the good energy resolution and low background. Metal massto‐light ratios were derived and we will discuss the origin of the metals. We also review the results of the search for bulk motion and hard X‐ray emission. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
58.
A. Mahabal S.G. Djorgovski M. Turmon J. Jewell R.R. Williams A.J. Drake M.G. Graham C. Donalek E. Glikman Palomar‐QUEST team 《Astronomische Nachrichten》2008,329(3):288-291
There is an increasing number of large, digital, synoptic sky surveys, in which repeated observations are obtained over large areas of the sky in multiple epochs. Likewise, there is a growth in the number of (often automated or robotic) follow‐up facilities with varied capabilities in terms of instruments, depth, cadence, wavelengths, etc., most of which are geared toward some specific astrophysical phenomenon. As the number of detected transient events grows, an automated, probabilistic classification of the detected variables and transients becomes increasingly important, so that an optimal use can be made of follow‐up facilities, without unnecessary duplication of effort. We describe a methodology now under development for a prototype event classification system; it involves Bayesian and Machine Learning classifiers, automated incorporation of feedback from follow‐up observations, and discriminated or directed follow‐up requests. This type of methodology may be essential for the massive synoptic sky surveys in the future. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
59.
J. Radebaugh R.D. Lorenz S.D. Wall E. Reffet R.M. Lopes L. Soderblom M. Janssen P. Callahan the Cassini Radar Team 《Icarus》2008,194(2):690-703
Thousands of longitudinal dunes have recently been discovered by the Titan Radar Mapper on the surface of Titan. These are found mainly within ±30° of the equator in optically-, near-infrared-, and radar-dark regions, indicating a strong proportion of organics, and cover well over 5% of Titan's surface. Their longitudinal duneform, interactions with topography, and correlation with other aeolian forms indicate a single, dominant wind direction aligned with the dune axis plus lesser, off-axis or seasonally alternating winds. Global compilations of dune orientations reveal the mean wind direction is dominantly eastwards, with regional and local variations where winds are diverted around topographically high features, such as mountain blocks or broad landforms. Global winds may carry sediments from high latitude regions to equatorial regions, where relatively drier conditions prevail, and the particles are reworked into dunes, perhaps on timescales of thousands to tens of thousands of years. On Titan, adequate sediment supply, sufficient wind, and the absence of sediment carriage and trapping by fluids are the dominant factors in the presence of dunes. 相似文献
60.