Book reviews     

Roy  B. K.  Stanley  William R.  Bronger  Dirk  Dlin  Norman  Kukliński  Antoni  Cori  Berardo  Babikir  A. A. A.  Kunkel  G.  César  N.  Martin  Kähler 《GeoJournal》1989,18(2):255-260

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Tides and Arp's hypothesis about distribution of Hii regions     

Teresa Grabińska  Mirosław Zabierowski 《Astrophysics and Space Science》1979,66(2):503-504

We discuss Arp's hypothesis that the HII regions are more numerous and more conspicuous on the side of a galaxy facing its companion. Arp's hypothesis seems not to be true if we add to Hodge's sets of galaxies only the most probably tidally-interacting cases.  相似文献   

Discovery of powerful millisecond flares from Cygnus X-1     

Marek Gierli&#;ski  Andrzej A. Zdziarski 《Monthly notices of the Royal Astronomical Society》2003,343(3):L84-L88

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The asymmetry of the velocity distribution in the rotating ring in U Gem stars     

B. Paczyński  S. L. Piotrowski  W. Turski 《Astrophysics and Space Science》1968,2(2):254-257

It is shown that the non-keplerian character of the rotation of the ring of gas particles in a close binary system gives too large an amplitude of the radial velocity curve if this amplitude is determined from the positions of the emission lines of the ring.  相似文献   

CO 2 emission trading model with trading prices     

Jarosław Stańczak  Paweł Bartoszczuk 《Climatic change》2010,103(1-2):291-301

In this paper we consider the buying/selling prices of carbon dioxide (CO₂) emission permits in trading models with uncertainty. Permission prices, although usually omitted from standard models, may significantly influence the trading market. We thus undertook to construct a more realistic trade model and to compare it with the standard one. To do this, we introduced several important changes to the standard model, namely, (1) a new optimized quality function; and (2) transactions with price negotiations between regions. We also enhanced the model using methods described in the literature to allow it to deal with reported emissions uncertainty. Additionally, we used an original method of simulating this kind of market based on a specialized evolutionary algorithm (EA).  相似文献   

Scaling of tropical rainfall as observed by TRMM precipitation radar     

Mekonnen Gebremichael  Witold F. Krajewski  Thomas M. Over  Yukari N. Takayabu  Phillip Arkin  M. Katayama 《Atmospheric Research》2008,88(3-4):337-354

We used a three-year (1998–2000) dataset of TRMM Precipitation Radar observations to investigate the scaling properties of spatial rainfall fields. This dataset allows consideration of spatial scales ranging from about 4.3 km to 138 km and short temporal scales corresponding to the sensor overpasses. The focus is on the marginal spatial moment scaling, which allows estimation of the scaling parameters from a single scene of data. Here we present a global perspective of the scaling properties of tropical rainfall in terms of its spatial variability, atmospheric forcing, predictability, and applicability. Our results reveal the following: 1) the scaling parameters exhibit strong variability associated with land/ocean contrast and mean precipitation at the synoptic scale; 2) there exists a one-to-one relationship between the scaling parameters and the large-scale spatial average rain rate of a universal functional form; 3) the majority of the scenes are consistent with the hypothesis of scale invariance at the moment orders of 0 and 2; 4) relatively there are more scale-invariant rain scenes over land than over ocean; and 5) for the scenes that are non-scale-invariant, deviation from scale-invariance mainly arises from the increasingly intermittent behavior of rainfall as spatial scale decreases. These results have important implications for the development and calibration of downscaling procedures designed to reproduce rainfall properties at different spatial scales and lead to a better understanding of the nature of tropical rainfall at various spatial resolutions.  相似文献   

Repeating microlensing events in the OGLE data     

J. Skowron  &#;. Wyrzykowski  S. Mao  M. Jaroszy&#;ski 《Monthly notices of the Royal Astronomical Society》2009,393(3):999-1009

Microlensing events are usually selected among single-peaked non-repeating light curves in order to avoid confusion with variable stars. However, a microlensing event may exhibit a second microlensing brightening episode when the source or/and the lens is a binary system. A careful analysis of these repeating events provides an independent way to study the statistics of wide binary stars and to detect extrasolar planets. Previous theoretical studies predicted that 0.5–2 per cent of events should repeat due to wide binary lenses. We present a systematic search for such events in about 4000 light curves of microlensing candidates detected by the Optical Gravitational Lensing Experiment (OGLE) towards the Galactic bulge from 1992 to 2007. The search reveals a total of 19 repeating candidates, with six clearly due to a wide binary lens. As a by-product, we find that 64 events (∼2 per cent of the total OGLE-III sample) have been misclassified as microlensing; these misclassified events are mostly nova or other types of eruptive stars. The number and importance of repeating events will increase considerably when the next-generation wide-field microlensing experiments become fully operational in the future.  相似文献   

Double radio peak and non-thermal collimated ejecta in RS Ophiuchi following the 2006 outburst     

S. P. S. Eyres  T. J. O'Brien  R. Beswick  T. W. B. Muxlow  G. C. Anupama  N. G. Kantharia  M. F. Bode  M. P. Gawro&#;ski  R. Feiler  A. Evans  M. T. Rushton  R. J. Davis  T. Prabhu  R. Porcas  B. J. M. Hassall 《Monthly notices of the Royal Astronomical Society》2009,395(3):1533-1540

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Binary gas sorption/desorption experiments on a bituminous coal: Simultaneous measurements on sorption kinetics,volumetric strain and acoustic emission     

Zofia Majewska  Grażyna Ceglarska-Stefańska  Stanisław Majewski  Jerzy Ziętek 《International Journal of Coal Geology》2009,77(1-2):90-102

There is still no clear understanding of the specific interactions between coal and gas molecules. In this context sorption–desorption studies of methane and carbon dioxide, both in a single gas environment and gas mixtures, are of fundamental interest. This paper presents the results of unique simultaneous measurements of sorption kinetics, volumetric strain and acoustic emission (AE) on three tetragonal coal samples subjected to sorption of carbon dioxide and methane mixtures. The coal was a high volatile bituminous C coal taken from the Budryk mine in the Upper Silesia Basin, Poland. Three different gas mixtures were used in the sorption tests, with dominant CO₂, with dominant CH₄ and a 50/50 mixture.The experimental set-up was designed specially for this study. It consisted of three individual units working together: (i) a unit for gas sorption experiments using a volumetric method, (ii) an AE apparatus for detecting, recording and analysing AE, and (iii) a strain meter for measuring strains induced in the coal sample by gas sorption/desorption. All measurements were computer aided.The experiments indicated that the coal tested showed preferential sorption of CH₄ at 2.6 MPa pressure and exhibited comparable affinities for CH₄ and CO₂ at higher pressures (4.0 MPa). The results of chromatographic analysis of the gas released on desorption suggested that the desorption of methane from the coal was favoured. The relationship between the volumetric strain and the amount of sorbed gas was found to be non-linear. These results were contrary to common opinions on the coal behaviour. Furthermore, it appeared that the swelling/shrinkage of coal was clearly influenced by the network of fractures. Besides, the AE and strain characteristics suggested common sources of sorption induced AE and strain.The present results may have implications for the sequestration of carbon dioxide in coal seams and enhanced coalbed methane recovery (ECBM).  相似文献   

High-frequency X-ray variability as a mass estimator of stellar and supermassive black holes     

Marek Gierli&#;ski  Marek Niko&#;ajuk  Bo&#;ena Czerny 《Monthly notices of the Royal Astronomical Society》2008,383(2):741-749

There is increasing evidence that supermassive black holes in active galactic nuclei (AGN) are scaled-up versions of Galactic black holes. We show that the amplitude of high-frequency X-ray variability in the hard spectral state is inversely proportional to the black hole mass over eight orders of magnitude. We have analysed all available hard-state data from RXTE of seven Galactic black holes. Their power density spectra change dramatically from observation to observation, except for the high-frequency (≳10 Hz) tail, which seems to have a universal shape, roughly represented by a power law of index −2. The amplitude of the tail,   C _M   (extrapolated to 1 Hz), remains approximately constant for a given source, regardless of the luminosity, unlike the break or quasi-periodic oscillation frequencies, which are usually strongly correlated with luminosity. Comparison with a moderate-luminosity sample of AGN shows that the amplitude of the tail is a simple function of black hole mass,   C _M = C / M   , where   C ≈ 1.25 M_⊙ Hz⁻¹  . This makes   C _M   a robust estimator of the black hole mass which is easy to apply to low- to moderate-luminosity supermassive black holes. The high-frequency tail with its universal shape is an invariant feature of a black hole and, possibly, an imprint of the last stable orbit.  相似文献