RAPID: A fast,high resolution,flux-conservative algorithm designed for planet–disk interactions     

L.R. Mudryk  N.W. Murray 《New Astronomy》2009,14(1):71-87

We describe a newly developed hydrodynamic code for studying accretion disk processes. The numerical method uses a finite volume, non-linear, Total Variation Diminishing (TVD) scheme to capture shocks and control spurious oscillations. It is second-order accurate in time and space and makes use of a FARGO-type algorithm to alleviate Courant–Friedrichs–Lewy time step restrictions imposed by the rapidly rotating inner disk region. OpenMP directives are implemented enabling faster computations on shared-memory, multi-processor machines. The resulting code is simple, fast and memory efficient. We discuss the relevant details of the numerical method and provide results of the code’s performance on standard test problems. We also include a detailed examination of the code’s performance on planetary disk–planet interactions. We show that the results produced on the standard problem setup are consistent with a wide variety of other codes.  相似文献   

The small scatter in BH–host correlations and the case for self-regulated BH growth     

Philip F. Hopkins  Norman Murray †  Todd A. Thompson 《Monthly notices of the Royal Astronomical Society》2009,398(1):303-311

Supermassive black holes (BHs) obey tight scaling relations between their mass and host galaxy properties such as total stellar mass, velocity dispersion and potential well depth. This has led to the development of self-regulated models for BH growth, in which feedback from the central BH halts its own growth upon reaching a critical threshold. However, models have also been proposed in which feedback plays no role: so long as a fixed fraction of the host gas supply is accreted, relations like those observed can be reproduced. Here, we argue that the scatter in the observed BH–host correlations presents a demanding constraint on any model for these correlations, and that it favours self-regulated models of BH growth. We show that the scatter in the stellar mass fraction within a radius R in observed ellipticals and spheroids increases strongly at small R . At a fixed total stellar mass (or host velocity dispersion), on very small scales near the BH radius of influence, there is an order-of-magnitude scatter in the amount of gas that must have entered and formed stars. In short, the BH appears to 'know more' about the global host galaxy potential on large scales than the stars and gas supply on small scales. This is predicted in self-regulated models; however, models where there is no feedback would generically predict order-of-magnitude scatter in the BH–host correlations. Likewise, models in which the BH feedback in the 'bright' mode does not regulate the growth of the BH itself, but sets the stellar mass of the galaxy by inducing star formation or blowing out a mass in gas much larger than the galaxy stellar mass, are difficult to reconcile with the scatter on small scales.  相似文献   

Strategies for spectroscopy on Extremely Large Telescopes – II. Diverse-field spectroscopy     

G. J. Murray  J. R. Allington-Smith 《Monthly notices of the Royal Astronomical Society》2009,399(1):209-218

The fields of view of Extremely Large Telescopes will contain vast numbers of spatial sampling elements (spaxels) as their adaptive optics systems approach the diffraction limit over wide fields. Since this will exceed the detection capabilities of any realistic instrument, the field must be dilutely sampled to extract spectroscopic data from selected regions of interest. The scientific return will be maximized if the sampling pattern provides an adaptable combination of separated independent spaxels and larger contiguous subfields, seamlessly combining integral-field and multiple-object spectroscopy. We illustrate the utility of this diverse-field spectroscopy (DFS) to cosmological studies of galaxy assembly. We show how to implement DFS with an instrument concept: the Celestial Selector. This integrates highly multiplexed monolithic fibre systems and switching networks of the type currently available in the telecommunications industry. It avoids bulky moving parts, whose limitations were noted in Paper I. In Paper III, we will investigate the optimization of such systems by varying the input–output mapping.  相似文献   

On the nature of superoutbursts in dwarf novae   总被引：1，自引：0，他引：1  

M.R. Truss  J.R. Murray  G.A. Wynn 《Monthly notices of the Royal Astronomical Society》2001,324(1):L1-L5

We determine a crucial feature of the dark halo density distribution from the fact that the luminous matter dominates the gravitational potential at about one disc scalelength R _d, but at the optical edge     the dark matter has already become the main component of the galaxy density. From the kinematics of 137 spirals we find that the dark matter halo density profiles are self-similar at least out to R _opt and show core radii much larger than the corresponding disc scalelengths. The luminous regions of spirals consist of stellar discs embedded in dark haloes with roughly constant density. This invariant dark matter profile is very difficult to reconcile with the fundamental properties of the density distribution of cold dark matter haloes. With respect to previous work, the present evidence is obtained by means of a robust method and for a large and complete sample of normal spirals.  相似文献   

Magnetically warped discs in close binaries     

James R. Murray  Dalia Chakrabarty  Graham A. Wynn  Louisa Kramer 《Monthly notices of the Royal Astronomical Society》2002,335(2):247-255

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A model for the statistical distribution of microlithotypes in coal     

Murray A. Cameron  John W. Hunt 《Mathematical Geology》1985,17(3):267-285

Microlithotype composition of a coal sample is often summarized by examining a large number (~500) of subsamples of a grain mount and estimating proportions of vitrite, intermediates, and inertite, where, for samples we have investigated, the proportion of intermediates is generally less than 0.4. This suggests that most subsamples are either greater than 95% vitrinite or greater than 95% inertinite, so that the statistical distribution of vitrinite has most of its weight in its tails. Two distributions which may have this shape are the beta and the logistic normal, and these have been fitted to the microlithotype distribution of some coal samples. Parameters of these fitted distributions are related to the proportion of vitrinite in the sample and thickness of microscopic bands in the coal. For coals in the Sydney Basin, at least, it was found that the parameter relating to band thickness is approximately constant over a coal seam; therefore, fitting one or other of these distributions to such data leads to directly interpretable parameters.  相似文献   

DISCUSSION OF "An Alternate Procedure for Analyzing Aquifer Tests Using the Theis Nonequilibrium Solution," by O. L. Franke, May–June 1987 issue, v. 25, no. 3, pp. 314–320.     

Willard A. Murray 《Ground water》1987,25(5):616-617

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Cryogenic Tests of Volume-Phase Holographic Gratings: I. Results at 200 K     

N. Tamura  G. J. Murray  P. Luke  C. Blackburn  D. J. Robertson  N. A. Dipper  R. M. Sharples  J. R. Allington-Smith 《Experimental Astronomy》2003,15(1):1-12

We present results from cryogenic tests of a Volume-Phase Holographic(VPH) grating at 200 K measured at near-infrared wavelengths. The aims of these tests were to see whether the diffraction efficiency and angular dispersion of a VPH grating are significantly different at a low temperature from those at a room temperature, and to see how many cooling and heating cycles the grating can withstand. We have completed 5 cycles between room temperature and 200 K, and find that the performance is nearly independent of temperature, at least over the temperature range which we are investigating. In future, we will not only try more cycles between these temperatures but also perform measurements at a much lower temperature (e.g., ∼80 K).  相似文献   

Reviews     

Murray McCaskill  David Wilmoth  Peter L. Simons  W. S. Logan  B. E. Riley  Noel G. De Souza 《The Australian geographer》1988,19(2):300-316

CUL DE SAC: The Question of New Zealand's Future by H. Franklin. 13 x 19 cm, 184 pages. Allen & Unwin: Sydney 1985 (ISBN 0 86861 514 5) $A12.95 (soft).

SHOPPING CENTRE DEVELOPMENT: Policies and Prospects edited by J. A. Dawson and J. D. Lord. 14 x 22 cm, 269 pages. Croom Helm: London 1985 (ISBN 0 7099 0845 8) $A49.95 (hard).

GENTRIFICATION OF THE CITY edited by N. Smith and P. Williams. 13 x 22 cm, xiii and 257 pages. Allen & Unwin: Boston 1986 (ISBN 0 04 301201 9) $A59.00 (hard); (ISBN 0 04 301202 7) $A26.95 (soft).

EUROPE TODAY: Countries and Issues by D. J. Davis and D. C. Flint. 19 x 27 cm, 256 pages. Bell & Hyman: London 1986 (ISBN 0 7135 2518 5) £5.95 (soft).

THE WORLD NOW (Australian edition) by A. Reed and R. Pask. 21 x 30 cm, 96 pages. Edward Arnold: Melbourne 1986 (ISBN 0 7131 8225 3) $A12.95 (soft).

THE INDO‐PACIFIC LIBRARY: Set Two — Ten Titles (11 Australia, 12 Burma, 13 French Polynesia, 14 India, 15 Laos and Kampuchea, 16 North and South Korea, 17 Pakistan and Bangladesh, 18 Sri Lanka, 19 Thailand, 20 Vietnam) by G. Houghton and J. Wakefield. 19 x 25 cm, 32 pages each. Macmillan: Melbourne 1987 $A9.95 (hard) each title.

THE INDO‐PACIFIC LIBRARY: Set Two — Macmillan Black Line Masters by G. Houghton and J. Wakefield. Macmillan: Melbourne 1987 (ISBN 0 333 43059 X) $A19.95 (soft).

QUEENSLAND: A Geographical Interpretation (Queensland Geographical Journal, 4th Series, Volume 1) edited by J. H. Holmes. 18 x 24 cm, 343 pages. Boolarong Publications: Brisbane 1986 (ISBN 0817 489X) $A25.00 (soft).

THE ROAD TO BOTANY BAY: An Essay in Spatial History by P. Carter. 14 x 22 cm, xv and 384 pages. Faber and Faber: London 1987 (ISBN 0 571 14551 5) $A29.95 (hard).

AN EVALUATION OF LOCAL AREA ECONOMIC STRATEGY STUDIES (Australian Regional Developments, No. 6) edited by J. D. Conroy. 30 x 21 cm, vii and 102 pages. Australian Government Publishing Service: Canberra 1987 (ISBN 0 644 06161 8).

PRODUCTION, WORK, TERRITORY: The Geographical Anatomy of Industrial Capitalism edited by A. J. Scott and M. Storper. 15 x 23 cm, xix and 344 pages. Allen & Unwin Inc: Boston 1986 (ISBN 0 04 338126 X) $A90.00 (hard); (ISBN 0 04 338127 8) $A38.95 (soft).

ANALYTICAL BEHAVIOURAL GEOGRAPHY by R. G. Golledge and R. J. Stimson. 16 x 24 cm, 345 pages. Croom Helm: London 1987 (ISBN 0 7099 3844 6) $A122.95 (hard).

AMBIGUOUS ALTERNATIVE: Tourism in Small Developing Countries edited by S. Britton and W. C. Clarke. 20 x 21 cm, 194 pages. University of the South Pacific: Suva 1987 (ISBN 982 01 0009); available from Geography Department, University of the South Pacific, Box 1168, Suva, Fiji.

AN ATLAS OF ENVIRONMENTAL AND RUMINANT POPULATION CHARACTERISTICS OF JAVA: A Multivariate Analysis Approach by J. M. Perkins, Armiadi Semali, P. W. Orchard and Rach‐met Rachman. 46 x 31 cm, 71 pages. Forage Research Project, University of New England: Armidale 1986 (ISBN 0 85834 691 5) $A50.00 plus postage (developed countries); $A20.00 plus postage (developing countries).

ANTARCTICA: THE NEXT DECADE. Report of a Study Group (Studies in Polar Research) by A. Parsons et al. 15 x 23 cm, xii and 164 pages. Cambridge University Press: Cambridge 1987 (ISBN 0521 331811) $A65.00 (hard).

THE HUMAN IMPACT ON THE NATURAL ENVIRONMENT by A. Goudie, 25 x 17 cm, x and 338 pages. Basil Blackwell: Oxford 1986 (ISBN 0 631 13758 0) $A29.50 (soft).

ATMOSPHERIC POLLUTION: Causes, Effects and Control Policies by D. Elsom. 15 x 23 cm, x and 319 pages. Basil Blackwell: Oxford 1987 (ISBN 0 631 13813 3) $A122.50 (hard); (ISBN 0 631 15674 7) $A43.95 (soft).

SEA SURFACE STUDIES: A Global View edited by R. J. N. Devoy. 16 x 24 cm, 649 pages. Croom Helm: London 1987 (ISBN 0 7099 0871 7) £55.00 (hard).  相似文献   

Identification and explanation of continental differences in the variability of annual runoff     

Murray C. Peel  Thomas A. McMahon  Brian L. Finlayson  Fred G. R. Watson 《Journal of Hydrology》2001,250(1-4):224-240

Continental differences in the variability of annual runoff were investigated using an expanded and improved database to that used in previous work. A statistical analysis of the data, divided by continent and Köppen climate type, revealed that continental differences exist in the variability of annual runoff. The variability of annual runoff for temperate Australia, arid southern Africa and possibly temperate southern Africa were noted to be generally higher than that of other continents with data in the same climate type. A statistical analysis of annual precipitation by continent and Köppen climate type revealed that differences in the variability of annual precipitation could account for some but not all the observed differences in the variability of annual runoff. A literature review of potential causes of continental differences in evapotranspiration resulted in the hypothesis that the significantly higher variability of annual runoff in temperate Australia and possibly temperate southern Africa may be due to the distribution of evergreen and deciduous vegetation. The process model Macaque was used to test this hypothesis. The model results indicate that the variability of annual runoff may be between 1 and 99% higher for catchments covered in evergreen vegetation as opposed to deciduous vegetation, depending on mean annual precipitation and the seasonality of precipitation. It is suggested that the observed continental differences in the variability of annual runoff are largely caused by continental differences in the variability of annual precipitation and in temperate regions the distribution of evergreen and deciduous vegetation in conjunction with the distribution of mean annual precipitation and precipitation seasonality.  相似文献