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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Inversion of seismic reflection data from the Gialo Field, Sirte Basin

BenGheit, Ali O. January 1996 (has links)
This project is concerned with the development of software to invert seismic reflection data for acoustic impedance, with application to the YY-reservoir area in Gialo Field, Sirte Basin. The problem was that of inverting post-stack seismic reflection data from two seismic lines into impedance profiles. The main input to the inversion process is an initial guess, or initial earth model, of the impedance profile defined in terms of parameters. These parameters describe the impedance and the geometry of the number of layers that constitute the earth model. Additionally, an initial guess is needed for the seismic wavelet, defined in the frequency domain using nine parameters. The inversion is an optimisation problem subject to constraints. The optimisation problem is that of minimising the error energy function defined by the sum of squares of the residuals between the observed seismic trace and its prediction by the forward model for the given earth model parameters. To determine the solution we use the method of generalised linear inverses. The generalised inverse is possible only when the Hessian matrix, which describe the curvature of error energy surface, is positive definite. When the Hessian is not definite, it is necessary to modify it to obtain the nearest positive definite matrix. To modify the Hessian we used a method based on the Cholesky factorisation. Because the modified Hessian is positive definite, we need to find the generalised inverse only once. But we may need to restrict the step-length to obtain the minimum. Such a method is a step-length based method. A step-length based method was implemented using linear equality and inequality constraints into a computer program to invert the observed seismic data for impedance. The linear equality and inequality constraints were used so that solutions that are geologically feasible and numerically stable are obtained. The strategy for the real data inversion was to first estimate the seismic wavelet at the well, then optimise the wavelet parameters. Then use the optimum wavelet to invert for impedance and layer boundaries in the seismic traces. In the three real data examples studied, this inversion scheme proved that the delineation of the Chadra sands in Gialo Field is possible. Better results could be obtained by using initial earth models that properly parameterise the subsurface, and linear constraints that are based on well data. Defining the wavelet parameters in the time domain may prove to be more stable and could lead to better inversion results.

The design and simulation of a broadband directional array in a cylindrical waveguide

Aldana, Guillermo Emilio. January 2002 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Impedance measurement of local resonant sonic materials /

Cheng, Chun-kwong. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 69). Also available in electronic version. Access restricted to campus users.

Electric control of acoustic impedance

Cheung, Sung-man., 張宋文. January 2010 (has links)
published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Light weight low frequency sound focus lens /

Dai, Hin Man. January 2005 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 90). Also available in electronic version.

Characterisation of bubbles in liquids using acoustic techniques

Ramble, David Gary January 1997 (has links)
No description available.

In-situ Messung der akustischen (Wand-)Impedanz

Nocke, Christian, christian@nocke.de 24 March 2000 (has links)
No description available.

The design and simulation of a broadband directional array in a cylindrical waveguide

Aldana, Guillermo Emilio 28 August 2008 (has links)
Not available / text

Application of impedance tube technique in the measurement of burning solid propellant admittances

Salikuddin, Mohammed 05 1900 (has links)
No description available.

An investigation of the diffraction of an acoustic plane wave by a curved surface of finite impedance

Kearns, James A. 12 1900 (has links)
No description available.

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