Ultramafic-derived arsenic in a fractured bedrock aquifer     

Peter C. Ryan  Jonathan KimAndrew J. Wall  Jonathan C. MoenLilly G. Corenthal  Daniel R. ChowColleen M. Sullivan  Kevin S. Bright 《Applied Geochemistry》2011,26(4):444-457

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The Phoenix Deep Survey: X-ray properties of faint radio sources     

A. Georgakakis  A. M. Hopkins †  M. Sullivan  J. Afonso  I. Georgantopoulos  B. Mobasher  L. E. Cram 《Monthly notices of the Royal Astronomical Society》2003,345(3):939-948

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A milky way search strategy for extraterrestial intelligence     

Woodruft T. Sullivan  Kenneth J. Mighell 《Icarus》1984,60(3):675-684

It is assumed that the density of sites of technical civilizations emitting suitable signals (whether purposeful or unintentional) is proportional to the stellar density at any location in our Galaxy, as modeled by Bahcall and Soneira (1980, Astrophys. J. Suppl. Ser.44, 73–110). A wide variety of possible radio luminosity functionsφ(L)for these civilizations is then assumed and for each the number of detectable signals per square degree over the sky is calculated. It has been found that most detectable signals occur at galactic latitudes of 10° or less and longitudes within 90° of the galactic center, a region which covers only 9% of the entire sky. This result holds for a wide range ofφ(L) types, including Gaussian distributions and power law functions with slopes less than 2.5, or any combination of these. The Milky Way is much less preffered, but still advantageous, for cases of steep power law functions (slopes greater than 2.5) or Gaussian functions with mean luminosities so low that any existing civilizations can only be detected at small distances(<0.5 kpc). The only cases where low galactic latitudes are not advantageous are (1) for frequencies of operation less than 600 MHz where the deleterious effects on signal-to-noise ratios of the natural galactic background emission become dominant, and (2) in searches for narrowband(<1 Hz) signals at frequencies less than 2 GHz where significant interstellar broadening of signals occurs over distances of? 10 kpc. Furthermore, all of the above results have broader applicability: they are equally valid for searches for any type of natural radio phenomenon if its probability of occurence is proportional to stellar density. Therefore, for a nontargeted search, a Milky Way strategy which concentrates on the inner galactic plane is preferred. The factor of 10 in time saved over an all-sky survey can then be used for, say, increased sensitivity or a survey of nearby galaxies. For a targeted search, rather than searching the nearestn solar-like stars, time is more profitably spent, for example, on the very nearest0.1n stars plus the next nearest0.9n stars which are also within 10° of the galactic plane. This picks up the Milky Way background while only sacrificing a factor of 2 in the average distance to the target stars.  相似文献   

A high time resolution study of the solar wind-magnetosphere energy coupling function     

S.-I. Akasofu  J.F. Carbary  C.-I. Meng  J.P. Sullivan  R.P. Lepping 《Planetary and Space Science》1982,30(6):537-543

A high time resolution study of the relationship between the solar wind-magnetosphere energy coupling function ? and the total energy dissipation rate U_T of the magnetosphere is made using 5-min average values of solar wind data and of the geomagnetic indices AE and Dst. All the results are essentially the same as those obtained by the earlier studies which were based on the hourly average data set. Therefore, we confirm that the magnetosphere is primarily a driven system.  相似文献   

Error models for reducing history match bias     

A. O’Sullivan  M. Christie 《Computational Geosciences》2006,10(4):405-405

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Paleokarst system development in the San Andres Formation, Permian Basin, revealed by seismic characterization   总被引：1，自引：0，他引：1  

Qifeng Dou  Yuefeng Sun  Charlotte Sullivan  Hao Guo 《Journal of Applied Geophysics》2011,75(2):379-389

Paleokarst systems are one of the major factors resulting in carbonate reservoir heterogeneity and compartmentalization. Nevertheless, few effective workflows have been proposed to map the 3D distribution of such systems. We describe a detailed seismic characterization approach integrating core, well log and rock physics analysis, to reveal a complex subsurface paleokarst system in the San Andres Formation, Permian basin, West Texas. In the area of high volume production, the collapsed paleokarst system is characterized by irregularly developed crackle and fracture breccias, mosaic breccias and cave fillings in the Upper San Andres Formation, which are delineated using seismic acoustic impedance. Along the transition from platform to basin, the paleokarst system is marked by a linear collapse including sags and small vertical faults that are recognizable in seismic imaging. Production data indicates that tight paleokarst zones cause reservoir compartmentalization and influence fluid communication between wells. The complex paleokarst system development is explained using a carbonate platform hydrological model, an outcrop analogue similar to modern marine hydrological environments within carbonate islands. Our method of model development for complex subsurface paleokarst systems may be applicable to other paleoenvironments.  相似文献   

Equivalent viscous damping for steel concentrically braced frame structures   总被引：1，自引：1，他引：0  

K. K. Wijesundara  R. Nascimbene  T. J. Sullivan 《Bulletin of Earthquake Engineering》2011,9(5):1535-1558

The direct displacement based seismic design procedure utilises equivalent viscous damping expressions to represent the effect of energy dissipation of a structural system. Various expressions for the equivalent viscous damping of different structural systems are available in the literature, but the structural systems examined in the past have not included concentrically braced frame structures. Thus, this study describes the development of an equivalent viscous damping equation for concentrically braced frame structures based on the hysteretic response of 15 different single storey models. Initially, equivalent viscous damping is calculated based on the area based approach and then corrected for the earthquake excitation. An iterative procedure is adopted to calibrate the equivalent viscous damping expression to the results of inelastic time history analyses using a number of spectrum-compatible real accelerograms. From the results of this research, a new damping expression is developed as a function of the ductility and the non dimensional slenderness ratio.  相似文献   

Results of Seepage Meter and Mini-Piezometer Study, Lake Mead, Nevada   总被引：2，自引：1，他引：2  

William W. Woessner  Kevin E. Sullivan 《Ground water》1984,22(5):561-568

The seepage meter and the mini-piezometer were utilized in an attempt to evaluate ground-water reservoir interactions over a 12-month period at Echo Bay in Lake Mead. In conjunction with these techniques three standard piezometers, refraction seismic data, and water chemistry data were utilized to interpret seepage device results. During a four-month period, from December 1979 to March 1980, an 8 ft (2.5 m) rise in reservoir stage, the reservoir contributed water to Echo Wash bank storage at rates of up to 0.29 gpd/ft² (12 lpd/m²). Ground-water discharge occurred for the remainder of the project, during a stage decline from April 1980 to May 1980, a rise in June 1980, and leveling off and slight decline for the remainder of the year, July 1980 to December 1980. The maximum seepage meter ground-water discharge rate of 3.0 gpd/ft² (122 lpd/m²) was recorded in December 1980. Seepage meter water chemistry data for June were similar to Lake Mead water chemistry and were interpreted to be previously recharged Lake Mead water. September water chemistry data showed two possible components of ground-water discharge, a high SpC calcium sulfate Echo Wash ground water and a lower SpC Lake Mead recharged bank storage water. December ground-water chemistry data showed discharge to be a high SpC calcium sulfate water similar to Echo Wash ground-water quality which was apparently unaffected by Lake Mead inflow. Mini-piezometer data were collected at each seepage meter site. However, these data usually did not provide correlative results with seepage meter data probably because of suspended sediment in the piezometer water column and plugging of the perforated tip. Seepage meters were successfully utilized to characterize reservoir ground-water interaction in Echo Bay.  相似文献   

The feasibility and utility of a paleolimnology/paleoclimate data cooperative for North America   总被引：1，自引：0，他引：1  

T. J. Sullivan  D. F. Charles 《Journal of Paleolimnology》1994,10(3):265-273

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Precise calculation of the magnetosphere surface for a tilted dipole     

Joon Y. Choe  David B. Beard  Edward C. Sullivan 《Planetary and Space Science》1973,21(3):485-498

The shape of the magnetosphere has been calculated self-consistently for inclinations of the Earth's magnetic dipole from perpendicular to the solar wind. Inclination angles of 0–35° have been chosen in steps of 5° and various smooth trends in the surface characteristics with increasing inclination angle noted. The surface points and the complete field at the surface points have been calculated for the entire surfaces. The neutral point region has been given precise study in one degree steps and is found to be tangent to the solar wind velocity and to have a smooth continuous curvature. The inclusion of the Earth's bow shock pressure and other sources of current have not been included at this stage of our program.  相似文献