Spelling suggestions: "subject:"eismic"" "subject:"zeismic""
11 
Subcoal seismic exploration in the Gippsland Basin (Australia) /Dunne, Jarrod Craig. January 1996 (has links)
Thesis (Ph. D.)University of Melbourne, 1996. / Includes bibliographical references.

12 
A comparative study of the algebraic reconstruction technique and the constrained conjugate gradient method as applied to cross borehole geophysical tomographyMasuda, Ryuichi. January 1989 (has links)
Thesis (M.S.)Ohio University, June, 1989. / Title from PDF t.p.

13 
Subsurface electromagnetic sensing in the presence of the airearth interface using a crossborehole configuration /Ellis, Grant Andrew. January 1995 (has links)
Thesis (Ph. D.)University of Washington, 1995. / Vita. Includes bibliographical references (leaves [133]138).

14 
Wavelet estimation and debubbling using minimum entropy deconvolution and time domain linear inverse methodsLevy, Shlomo January 1979 (has links)
A new and different approach to the solution of the normal equations of minimum entropy deconvolution (MED) is developed. This approach which uses singular value decomposition in the iterative solution of the MED equations increases the signaltonoise ratio of the deconvolved output and enhances the resolution of MEC.
The problem of deconvolution, and in particular wavelet estimation, is formulated as a linear inverse problem. Both generalized linear inverse methods and BackusGilbert inversion are considered. The proposed wavelet estimation algorithm uses the MED output as a first approximation to the earth response. The approximated response and the observed seismograms serve as an input to the inversion schemes and the outputs are the estimated wavelets. The remarkable performance of the linear inverse schemes for cases of highly noisy data is demonstrated.
A debubbling example is used to show the completeness of the linear inverse schemes. First the wavelet estimation part was carried out and then the debubbling problem was formulated as a generalized linear inverse problem which was solved using the estimated wavelet.
This work demonstrates the power of the linear inverse schemes when dealing with highly noisy data. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

15 
Interferometric Imaging and its Application to 4D ImagingSinha, Mrinal 03 1900 (has links)
This thesis describes new interferometric imaging methods for migration and waveform
inversion. The key idea is to use reflection events from a known reference reflector
to ”naturally redatum” the receivers and sources to the reference reflector.
Here, ”natural redatuming” is a datadriven process where the redatuming Green’s
functions are obtained from the data. Interferometric imaging eliminates the statics
associated with the noisy overburden above the reference reflector.
To mitigate the defocussing caused by overburden errors I first propose the use
of interferometric leastsquares migration (ILSM) to estimate the migration image.
Here, a known reflector is used as the reference interface for ILSM, and the data
are naturally redatumed to this reference interface before imaging. Numerical results
on synthetic and field data show that ILSM can significantly reduce the defocussing
artifacts in the migration image.
Next, I develop a waveform tomography approach for inverting the velocity model
by mitigating the velocity errors in the overburden. Unresolved velocity errors in the
overburden velocity model can cause conventional fullwaveform inversion to get stuck
in a local minimum. To resolve this problem, I present interferometric fullwaveform
inversion (IFWI), where conventional waveform tomography is reformulated so a velocity
model is found that minimizes the objective function with an interferometric
crosscorrelogram misfit. Numerical examples show that IFWI, compared to FWI,
computes a significantly more accurate velocity model in the presence of a nearsurface
with unknown velocity anomalies.
I use IFWI and ILSM for 4D imaging where seismic data are recorded at different
times over the same reservoir. To eliminate the timevarying effects of the near
surface both data sets are virtually redatumed to a common reference interface before
migration. This largely eliminates the overburdeninduced statics errors in both data
sets. Results with synthetic and field data show that ILSM and IFWI can suppress
the artifacts caused by nonrepeatability in timelapse surveys. This can lead to a
much more accurate characterization of the movement of fluids over time. In turn,
this information can be used to optimize the extraction of resources in enhanced oil
recovery (EOR) operations.

16 
Residual migration velocity analysis in the plane wave domain theory and applications /Jiao, Junru, January 2001 (has links)
Thesis (Ph. D.)University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

17 
Residual migration velocity analysis in the plane wave domain : theory and applications /Jiao, Junru, January 2001 (has links)
Thesis (Ph. D.)University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 181185). Available also in a digital version from Dissertation Abstracts.

18 
Residual migration velocity analysis in the plane wave domain : theory and applicationsJiao, Junru, 1959 21 March 2011 (has links)
Not available / text

19 
A discreetscatterer model of the seismic P codaCraig, Mitchell Scott 05 1900 (has links)
No description available.

20 
StructureSpecific Probabilistic Seismic Risk AssessmentBradley, Brendon Archie January 2009 (has links)
This thesis addresses a diverse range of topics in the area of probabilistic seismic risk
analysis of engineering facilities. This intentional path of diversity has been followed
primarily because of the relatively new and rapid development of this facet of earthquake
engineering. As such this thesis focuses on the rigorous scrutinization of current, and in
particular, simplified methods of seismic risk assessment; the development of novel aspects
of a risk assessment methodology which provides easily communicated performance
measures and explicit consideration for the many uncertainties in the entire earthquake
problem; and the application of this methodology to casestudy examples including structures
supported on pile foundations embedded in liquefiable soils.
The stateoftheart in seismic risk and loss assessment is discussed via the case study
of a 10 storey New Zealand office building. Particular attention is given to the quality and
quantity of information that such assessment methodologies provide to engineers and
stakeholders for rational decisionmaking.
Two chapters are devoted to the investigation of the powerlaw model for representing
the ground motion hazard. Based on the inaccuracy of the powerlaw model at representing
the seismic hazard over a wide range of exceedance rates, an alternative, more accurate,
parametric hazard model based on a hyperbola in loglog space is developed and applied to
New Zealand peak ground acceleration and spectral acceleration hazard data. A semianalytical
closedform solution for the demand hazard is also developed using the hyperbolic
hazard model and applied for a casestudy performance assessment. The powerlaw hazard
model is also commonly used to obtain a closedform solution for the annual rate of structural
collapse (collapse hazard). The magnitude of the error in this closedform solution due to
errors in the necessary functional forms of its constitutive relations is examined via a
parametric study.
A series of seven chapters are devoted to the further development of various aspects of
a seismic risk assessment methodology. Intensity measures for use in the estimation of
spatially distributed seismic demands and seismic risk assessment which are: easily
predicted; can predict seismic response with little uncertainty; and are unbiased regarding additional properties of the input ground motions are examined. An efficient numerical
integration algorithm which is specifically tailored for the solution of the governing risk
assessment equations is developed and compared against other common methods of
numerical integration. The efficacy of approximate uncertainty propagation in seismic risk
assessment using the socalled FirstOrder SecondMoment method is investigated.
Particular attention is given to the locations at which the approximate uncertainty propagation
is used, the possible errors for various computed seismic risk measures, and the reductions in
computational demands. Component correlations have to date been not rigorously considered
in seismic loss assessments due to complications in their estimation and tractable
methodologies to account for them. Rigorous and computationally efficient algorithms to
account for component correlations are presented. Particular attention is also given to the
determination of correlations in the case of limited empirical data, and the errors which may
occur in seismic loss assessment computations neglecting proper treatment of correlations are
examined. Trends in magnitude, distribution, and correlation of epistemic uncertainties in
seismic hazard analyses for sites in the San Francisco bay area are examined. The
characteristics of these epistemic uncertainties are then used to compare and contrast three
methods which can be used to propagate such uncertainties to other seismic risk measures.
Causes of epistemic uncertainties in component fragility functions, their evaluation, and
combination are also examined.
A series of three chapters address details regarding the seismic risk assessment of
structures supported on pile foundations embedded in liquefiable soils. A ground motion
prediction equation for spectrum intensity (found to be a desirable intensity measure for
seismic response analysis in liquefiable soils) is developed based on ground motion
prediction equations for spectral accelerations, which are available in abundance in literature.
Determination of intensity measures for the seismic response of pile foundations, which are
invariably located in soil deposits susceptible to liquefaction, is examined. Finally, a rigorous
seismic performance and loss assessment of a casestudy bridge structure is examined using
rigorous ground motion selection, seismic effective stress analyses, and professional cost
estimates. Both direct repair and loss of functionality consequences for the bridge structure
are examined.

Page generated in 0.0365 seconds