Thermal properties and coal rank in rocks and coal seams of the southern Sydney Basin,new South Wales: A palaeogeothermal explanation of coalification     

R.A. Facer  A.C. Cook  A.E. Beck 《International Journal of Coal Geology》1980,1(1):1-17

Measurements of thermal conductivity on 106 disc specimens of rocks from 275 m of the Permian to Triassic section of the Southern Coalfield of the southern Sydney Basin have been carried out in an effort to explain a high rank gradient in the Permian coals. The samples came from six diamond drill holes north and west of Wollongong, although one hole only provided specimens of a syenitic sill (n = 17, mean thermal conductivity = 2.36 W/m°K, s.d. 0.03). When combined with previously published data on chip specimens, with which there is good agreement, from a further four drill holes the mean thermal conductivity for the late Permian and early Triassic sandstones and shales is 3.20 W/m°K.Heat generation by Permian volcanic rocks below the coal measures (from about 1 to 3 μW/m³), and by basement granitic rocks, appears to be consistent with previously reported heat flow for the southern Sydney Basin (about 80 mW/m²). This heat flow is a relatively high value for the east coast of Australia. Younger (Mesozoic and Tertiary) intrusive and extrusive igneous rocks produce local coal-rank anomalies, but do not appear to have any regional effect.The rank of coals above the Permian volcanic rocks appears to be little affected by the presence of the igneous rocks and the coal-rank decreases towards the major area of vulcanicity. Organic matter in sedimentary rocks interbedded with the volcanic rocks is of relatively high rank but it appears that these thermal effects do not extend more than about 100 m above the base of the coal measures. The area of high rank north and northwest of Wollongong seems likely to be a regional effect associated with a combination of high heat generation in basement and the Permian rocks, and high heat flow from the basement. Greater cover on the coal measures, together with an increase in the proportion of rocks of relatively low thermal conductivity in the cover, may also influence the rank in the Permian coal.  相似文献   

Structural identification using linear models and earthquake records     

James L. Beck  Paul C. Jennings 《地震工程与结构动力学》1980,8(2):145-160

The problem of determining linear models of structures from seismic response data is investigated using ideas from the theory of system identification. The approach is to determine the optimal estimates of the model parameters by minimizing a selected measure-of-fit between the responses of the structure and the model. Because earthquake records are normally available from only a small number of locations in a structure, and because of noise in the records, it is necessary in practice to estimate parameters of the dominant modes in the records, rather than the stiffness and damping matrices of the linear model. A new algorithm is developed to determine the optimal estimates of the modal parameters. After tests with simulated data, the method is applied to a multi-storey building using records from the 1971 San Fernando earthquake in California. New information is obtained concerning the properties of the lower modes of the building and the time-varying character of the equivalent linear parameters.  相似文献   

A Study of Ozone Laminae Using Diabatic Trajectories, Contour Advection and Photochemical Trajectory Model Simulations.     

S. J. Reid  M. Rex  P. Von Der Gathen  I. Fløisand  F. Stordal  G. D. Carver  A. Beck  E. Reimer  R. Krüger-Carstensen  L. L. De Haan  G. Braathen  V. Dorokhov  H. Fast  E. Kyrö  M. Gil  Z. Lityñska  M. Molyneux  G. Murphy  F. O'Connor  F. Ravegnani  C. Varotsos  J. Wenger  C. Zerefos 《Journal of Atmospheric Chemistry》1998,30(1):187-207

In this paper, we show that the rate of ozone loss in both polar and mid-latitudes, derived from ozonesonde and satellite data, has almost the same vertical distribution (although opposite sense) to that of ozone laminae abundance. Ozone laminae appear in the lower stratosphere soon after the polar vortex is established in autumn, increase in number throughout the winter and reach a maximum abundance in late winter or spring. We indicate a possible coupling between mid-winter, sudden stratospheric warmings (when the vortex is weakened or disrupted) and the abundance of ozone laminae using a 23-year record of ozonesonde data from the World Ozone Data Center in Canada combined with monthly-mean January polar temperatures at 30 hPa.Results are presented from an experiment conducted during the winter of 1994/95, in phase II of the Second European Stratospheric And Mid-latitude Experiment (SESAME), in which 93 ozone-enhanced laminae of polar origin observed by ozonesondes at different time and locations are linked by diabatic trajectories, enabling them to be probed twice or more. It is shown that, in general, ozone concentrations inside laminae fall progressively with time, mixing irreversibly with mid-latitude air on time-scales of a few weeks. A particular set of laminae which advected across Europe during mid February 1995 are examined in detail. These laminae were observed almost simultaneously at seven ozonesonde stations, providing information on their spatial scales. The development of these laminae has been modelled using the Contour Advection algorithm of Norton (1994), adding support to the concept that many laminae are extrusions of vortex air. Finally, a photochemical trajectory model is used to show that, if the air in the laminae is chemically activated, it will impact on mid-latitude ozone concentrations. An estimate is made of the potential number of ozone molecules lost each winter via this mechanism.  相似文献   

Model Simulations on the Variability of Particulate MSA to Non-Sea-Salt Sulfate Ratio in the Marine Environment     

Veli-Matti Kerminen  Risto E. Hillamo  Anthony S. Wexler 《Journal of Atmospheric Chemistry》1998,30(3):345-370

A box model was constructed to investigate connections between the particulate MSA to non-sea-salt sulfate ratio, R, and DMS chemistry in a clean marine boundary layer. The simulations demonstrated that R varies widely with particle size, which must be taken into account when interpreting field measurements or comparing them with each other. In addition to DMS gas-phase chemistry, R in the submicron size range was shown to be sensitive to the factors dictating sulfate production via cloud processing, to the removal of SO₂ from the boundary layer by dry deposition and sea-salt oxidation, to the entrainment of SO₂ from the free troposphere, to the relative concentration of sub- and supermicron particles, and to meteorology. Three potential explanations for the increase of R toward high-latitudes during the summer were found: larger MSA yields from DMS oxidation at high latitudes, larger DMSO yields from DMS oxidation followed by the conversion of DMSO to MSA at high latitudes, or lower ambient H₂O₂ concentrations at high latitudes leading to less efficient sulfate production in clouds. Possible reasons for the large seasonal amplitude of R at mid and high latitudes include seasonal changes in the partitioning of DMS oxidation to the OH and NO₃ initiated pathways, seasonal changes in the concentration of species participating the DMS-OH reaction pathway, or the existence of a SO₂ source other than DMS oxidation in the marine boundary layer. Even small anthropogenic perturbations were shown to have a potential to alter the MSA to non-sea-salt sulfate ratio.  相似文献   

Second order elasticity theory: An improved formulation of the Grüneisen parameter at high pressure     

Anthony J. Falzone  Frank D. Stacey 《Physics of the Earth and Planetary Interiors》1981,24(4):284-290

The second order theory of elasticity, in which terms to second order in strain are retained in calculating atomic bond length changes and elastic moduli, is extended to describe thermal vibration of a face-centred cubic crystal. Coupled with equations relating the pressure dependences of elastic constants, this yields a new formulation of the thermal Grüneisen parameter γ in terms of pressure P, incompressibility K and rigidity, μ where f = 24 (3 K ? 2 P)/(3 K + 115 μ + 90 P). The factor f arises from bond interactions and the case f = 1, representing independent bonds (no interactions), yields the free-volume γ- Since we have shown earlier that the second order elasticity theory provides a convincing explanation of the elasticity of the inner core, we believe that the new formula is appropriate for the inner core. It is, however, inadequate to describe the lower mantle γ, in which atomic bond angle rigidity, not considered here, may be appreciable.  相似文献   

Latin America: Contesting extraction, producing geographies   总被引：3，自引：3，他引：0  

Anthony Bebbington 《Singapore journal of tropical geography》2009,30(1):7-12

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Direct impacts of alternative energy scenarios on water demand in the Middle East and North Africa   总被引：1，自引：1，他引：0  

Kerstin Damerau  Oscar P. R. van Vliet  Anthony G. Patt 《Climatic change》2015,130(2):171-183

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Projected changes in diverse ecosystems from climate warming and biophysical drivers in northwest Alaska     

Mark Torre Jorgenson  Bruce G. Marcot  David K. Swanson  Janet C. Jorgenson  Anthony R. DeGange 《Climatic change》2015,130(2):131-144

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The Wide Field Spectrograph (WiFeS): performance and data reduction     

Michael Dopita  Jonghwan Rhee  Catherine Farage  Peter McGregor  Gabe Bloxham  Anthony Green  Bill Roberts  Jon Neilson  Greg Wilson  Peter Young  Peter Firth  Gianni Busarello  Paola Merluzzi 《Astrophysics and Space Science》2010,327(2):245-257

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Exchange of ejecta between Telesto and Calypso: Tadpoles, horseshoes, and passing orbits     

Anthony R. Dobrovolskis  José Luis Alvarellos  Jack J. Lissauer 《Icarus》2010,210(1):436-445

We have numerically integrated the orbits of ejecta from Telesto and Calypso, the two small Trojan companions of Saturn’s major satellite Tethys. Ejecta were launched with speeds comparable to or exceeding their parent’s escape velocity, consistent with impacts into regolith surfaces. We find that the fates of ejecta fall into several distinct categories, depending on both the speed and direction of launch.The slowest ejecta follow suborbital trajectories and re-impact their source moon in less than one day. Slightly faster debris barely escape their parent’s Hill sphere and are confined to tadpole orbits, librating about Tethys’ triangular Lagrange points L₄ (leading, near Telesto) or L₅ (trailing, near Calypso) with nearly the same orbital semi-major axis as Tethys, Telesto, and Calypso. These ejecta too eventually re-impact their source moon, but with a median lifetime of a few dozen years. Those which re-impact within the first 10 years or so have lifetimes near integer multiples of 348.6 days (half the tadpole period).Still faster debris with azimuthal velocity components ?10 m/s enter horseshoe orbits which enclose both L₄ and L₅ as well as L₃, but which avoid Tethys and its Hill sphere. These ejecta impact either Telesto or Calypso at comparable rates, with median lifetimes of several thousand years. However, they cannot reach Tethys itself; only the fastest ejecta, with azimuthal velocities ?40 m/s, achieve “passing orbits” which are able to encounter Tethys. Tethys accretes most of these ejecta within several years, but some 1% of them are scattered either inward to hit Enceladus or outward to strike Dione, over timescales on the order of a few hundred years.  相似文献