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CreatorTitleDescriptionSubjectDate
76 Zhdanov, MichaelQuasi-analytical boundary condition for three-dimensional finite difference electromagnetic modelingNumerical modeling of the quasi-static electromagnetic (EM) field in the frequency domain in a three-dimensional (3-D) inhomogeneous medium is a very challenging problem in computational physics. We present a new approach to the finite difference (FD) solution of this problem. The FD discretization ...2004-01-01
77 Zhdanov, Michael S.Novel approach to the model appraisal and resolution analysis of regularized geophysical inversionThe existing techniques for appraisal of geophysical inverse images are based on calculating the model resolution and the model covariance matrices. In some applications, however, it becomes desirable to evaluate the upper bounds of the variations in the solution of the inverse problem. It is possib...Geophysical inversion; Electromagnetic modeling; Cauchy inequality; Resolution analysis; Lanczos decomposition method; SLDM; Voisey's Bay; 3-D modeling2006
78 Zhdanov, Michael S.Integral equation method for 3D modeling of electromagnetic fields in complex structures with inhomogeneous background conductivityWe present a new formulation of the integral equation (IE) method for three-dimensional (3D) electromagnetic (EM) modeling in complex structures with inhomogeneous background conductivity (IBC). This method overcomes the standard limitation of the conventional IE method related to the use of a horiz...3-D modeling; Integral equation method; Marine controlled-source electromagnetic data; MCSEM; Gemini Prospect; Gulf of Mexico2006
79 Jewell, PaulControls of tufa development in Pleistocene Lake Bonneville, UtahProminent tufa localities along the Provo level (∼14,000 14C yr B.P.) shoreline in Pleistocene Lake Bonneville have been characterized in detail. Three types of tufa are recognized: capping tufa, beachrock, and capping tufa over beachrock. Capping tufa and beachrock are end members of a continuum ...Tufa; Pleistocene; Pluvial lakes2006
80 Zhdanov, Michael S.Fast numerical modeling of multitransmitter electromagnetic data using multigrid quasi-linear approximationMultitransmitter electromagnetic (EM) surveys are widely used in remote-sensing and geophysical exploration. The interpretation of the multitransmitter geophysical data requires numerous three-dimensional (3-D) modelings of the responses of the receivers for different geoelectrical models of comple...Multitransmitter electromagnetic data; Numerical modeling; Multigrid quasi-linear approximation; Quasilinear approximation; geophysical exploration; 3-D modeling2006-06
81 Zhdanov, Michael S.Rigorous 3D inversion of marine CSEM data based on the integral equation methodMarine controlled-source electromagnetic (MCSEM) surveys have become an important part of offshore petroleum exploration. However, due to enormous computational difficulties with full 3D inversion, practical interpretation of MCSEM data is still a very challenging problem. We present a new approach ...2007
82 Chapman, David S.; Harris, Robert N.Stop-go temperature logging for precision applicationsWe describe a new field procedure for stop-go temperature logging of boreholes that attains millikelvin precision. Temperature is recorded continuously throughout the entire log, but the logging probe is held stationary for a fixed time at discrete depth intervals. Equilibrium temperatures at the di...Temperature logging; Boreholes; Stop-go logging method2007
83 Fernandez, Diego P.Deep-sea scleractinian coral age and depth distributions in the Northwest Atlantic over the last 225,000 yearsDeep-sea corals have grown for over 200,000 yrs on the New England Seamounts in the northwest Atlantic, and this paper describes their distribution both with respect to depth and time. Many thousands of fossil scleractinian corals were collected on a series o f cruises from 2003- 2005; by contrast,...Desmophyllum dianthus; Scleractinian coral; Seamounts; Northwest Atlantic2007
84 Fernandez, Diego P.Lowering the detection limit for arsenic: implications for a future practical quantitation limitExposure to arsenic (As) in drinking water is associated with an increased risk ol bladder, liver, kidney, ,ind skin cancers (Smith et al, 2002; NRG DIEGO P. FERNANDEZ, 2001). To mitigate these risks? the US Environmental Protection Agency AND JANET G. HERING (USEPA) revised the maximum contaminant ...Practical quantitation limit; Chlorine2007
85 Zhdanov, Michael S.Integral electric current method in 3-D electromagnetic modeling for large conductivity contrastAbstract-We introduce a new approach to 3-D electromagnetic (EM) modeling for models with large conductivity contrast. It is based on the equations for integral current within the cells of the discretization grid, instead of the electric field or electric current themselves, which are used in the c...Electromagnetic modeling; Integral electric current method; 3-D modeling; High conductivity contrast; Integral equations2007-05
86 Jarrard, Richard D.Exceptionally preserved jellyfishes from the Middle CambrianCnidarians represent an early diverging animal group and thus insight into their origin and diversification is key to understanding metazoan evolution. Further, cnidarian jellyfish comprise an important component of modern marine planktonic ecosystems. Here we report on exceptionally preserved cnida...Jellyfishes; Metazoan evolution; Jellyfish fossils; Marjum Formation; Utah; Middle Cambrian2007-10-31
87 Chapman, David S.Techniques, analysis, and noise in a Salt Lake Valley 4D gravity experimentRepeated high-precision gravity measurements using an automated gravimeter and analysis of time series of 1-Hz samples allowed gravity measurements to be made with an accuracy of 5 μGal or better. Nonlinear instrument drift was removed using a new empirical staircase function built from multiple ...Gravity measurements2008
88 Chapman, David S.Monitoring aquifer recharge using repeated high-precision gravity measurements: a pilot study in South Weber, UtahRepeated high-precision gravity surveys were conducted over two infiltration cycles on an alluvial-fan aquifer system at the mouth of Weber Canyon in northern Utah as part of the Weber River Basin Aquifer Storage and Recovery Pilot Project (WRBASR). Gravity measurements collected before, during, an...Aquifer recharge; Gravity measurements; Infiltration ponds; Weber River Basin Aquifer Storage and Recovery Pilot Project2008
89 Brown, Francis HaroldTiming of volcanism and evolution of the northern Kenya RiftThe northern Kenya Rift is bounded on the west by uplands of Turkana which comprise horst-like blocks that include metamorphic basement rocks, locally overlain unconformably by the Cretaceous Lubur Sandstone, in turn overlain by predominantly volcanic sequences in which relatively thin sedimentary p...2009
90 Zhdanov, MichaelLarge-scale 3D inversion of potential field dataInversion of gravity and/or magnetic data attempts to recover the density and/or magnetic susceptibility distribution in a 3D earth model for subsequent geological interpretation. This is a challenging problem for a number of reasons. First, airborne gravity and magnetic surveys are characterized b...2011
91 Zhdanov, MichaelLarge-scale 3D inversion of marine magnetotelluric data: Case study from the Gemini prospect, Gulf of MexicoThree-dimensional magnetotelluric (MT) inversion is an emerging technique for offshore hydrocarbon exploration. We have developed a new approach to the 3D inversion of MT data, based on the integral equation method. The Tikhonov regularization and physical constraint have been used to obtain a stab...2011
92 Zhdanov, MichaelThree-dimensional inversion of large-scale EarthScope magnetotelluric data based on the integral equation method: geoelectrical imaging of the Yellowstone conductive mantle plumeInterpretation of the EarthScope MT (magnetotelluric) data requires the development of a large-scale inversion method which can address two common problems of 3D MT inversion: computational time and memory requirements. We have developed an efficient method of 3D MT inversion based on an IE (integ...2011
93 Brown, Francis HaroldA reappraisal of the geomagnetic polarity time scale to 4 MA using data from the turkana basin, East AfricaRecalibration of the Pliocene and early Pleistocene geomagnetic time scale using the K-Ar dated fluvial sequence of the Turkana Basin in East Africa agrees with calibrations based on astronomical calculations. Ages estimated here are: Olduvai Subchron, 1.78-1.96 Ma; Reunion Subchrons, 2.11-2.15 Ma ...2012
94 Chapman, David S.Borehole temperatures and climate change: ground temperature change in south India over the past two centuriesVariations in surface g round temperature (SGT) at the Earth's surface diffuse downward in a predictable way causing systematic perturbations to the subsurface temperature field. The pioneering study of Lachenbruch and Marsh all [1986] in Alaska demonstrated that present-day borehole temperature-dep...2012-01-01
95 Chapman, David S.Air, ground, and groundwater recharge temperatures in an alpine setting, Brighton Basin, UtahNoble gases are useful tracers for constraining groundwater recharge temperature and elevation, critical in determining source areas of groundwater recharge in mountainous terrain. A monitoring network in the alpine Brighton Basin in the Wasatch Mountains of northern Utah, USA, was established to ex...2012-01-01
96 Zhdanov, MichaelDiscussion and reply: comments on "electromagnetic geophysics: notes from the past and the road ahead"The direct current and electromagnetic methods have been around for almost 180 years and have been applied successfully in mining, petroleum, geotechnical, engineering, environmental, groundwater, and tectonic studies. Over such a long period of time, it is possible to lose track of who the pioneers...2012-01-01
97 Zhdanov, Michael3D inversion of airborne electromagnetic dataTime-domain airborne surveys gather hundreds of thousands of multichannel, multicomponent samples. The volume of data and other complications have made 1D inversions and transforms the only viable method to interpret these data, in spite of their limitations. We have developed a practical methodolog...2012-01-01
98 Hu, LihaiTrace elements in the hairStudy of uneven distribution of trace elements in elephant hair and compare the result with animal horns.2013
99 Thorne, Michael S.Viterbi sparse spike detectionAccurate interpretation of seismic traveltimes and amplitudes in the exploration and global scales is complicated by the band-limited nature of seismic data. We discovered a stochastic method to reduce a seismic waveform into a most probable constituent spike train. Model waveforms were constructed ...2013-01-01
100 Solomon, Douglas KipTracer applications of noble gas radionuclides in the geosciencesNoble gas radionuclides, including 81Kr (t1/2 = 229,000 yr), 85Kr (t1/2 = 10.8 yr), and 39Ar (t1/2 = 269 yr), possess nearly ideal chemical and physical properties for studies of earth and environmental processes. Recent advances in Atom Trap Trace Analysis (ATTA), a laser-based atom counting method...2014-01-01
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