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Adjoint-based inverse determination ...

Liew, Haw Ling.

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Adjoint-based inverse determination of shear modulus and intraocular pressure.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Adjoint-based inverse determination of shear modulus and intraocular pressure./
Author:	Liew, Haw Ling.
Description:	120 p.
Notes:	Adviser: Peter M. Pinsky.
Contained By:	Dissertation Abstracts International67-09B.
Subject:	Applied Mechanics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3235267
ISBN:	9780542894855

Adjoint-based inverse determination of shear modulus and intraocular pressure.
Liew, Haw Ling.

Adjoint-based inverse determination of shear modulus and intraocular pressure. - 120 p.

Adviser: Peter M. Pinsky.

Thesis (Ph.D.)--Stanford University, 2006.

An elevated intraocular pressure (IOP) is a direct indication of glaucoma---a leading cause of blindness. The feasibility of a new waveform tonometry concept for simultaneous inverse determination of the IOP and the elasticity of human eye is explored in this research. This concept is based on the vibration characteristics of the eye. The biomechanical eye model is described by the boundary value problem of small fluid-structure interaction oscillation superimposed on a static configuration state corresponding to the initial large deformation due to the IOP loading. Since the response of the eye is a function of the elasticity and IOP, it is essential that the elastic moduli are recovered simultaneously with the IOP to render the determination objective. To recover the IOP, an inverse problem is formulated by minimization of a multiple-frequency residual functional which quantifies the deviation of the predicted displacements from the signature profiles. These distinctively different dynamic deformations at multiple frequencies lead to the regularization of the ill-posed inverse problem. A gradient-based algorithm is employed for the minimization, and the sensitivities are calculated by the adjoint method. For the computation of the multiple-frequency solutions and the sensitivities at each functional evaluation step, a full-field matrix-Pade via Lanczos technique is developed and it allows for simultaneous computation of these displacements and adjoint fields with the cost of essentially one factorization. By comparison to the stretching stiffness, the prestress is concluded to be a higher-order term; and its effect on the residual functional is improved by using waveform excitation. Since the prestress is due to the IOP loading, it must be determined to render the problem tractable. A closed-form expression for the prestress function is obtained by using an asymptotic procedure for the corneoscleral shell. Several inversion results are reported. The elastic moduli are accurately recovered, and hence render the IOP an objective measure.

ISBN: 9780542894855Subjects--Topical Terms:

1018410
Applied Mechanics.

Adjoint-based inverse determination of shear modulus and intraocular pressure.
LDR:02952nam 2200277 a 45 001 973195
005 20110928
008 110928s2006 eng d
020 $a 9780542894855
035 $a (UMI)AAI3235267
035 $a AAI3235267
040 $a UMI $c UMI
100 1 $a Liew, Haw Ling. $3 1297151
245 1 0 $a Adjoint-based inverse determination of shear modulus and intraocular pressure.
300 $a 120 p.
500 $a Adviser: Peter M. Pinsky.
500 $a Source: Dissertation Abstracts International, Volume: 67-09, Section: B, page: 5179.
502 $a Thesis (Ph.D.)--Stanford University, 2006.
520 $a An elevated intraocular pressure (IOP) is a direct indication of glaucoma---a leading cause of blindness. The feasibility of a new waveform tonometry concept for simultaneous inverse determination of the IOP and the elasticity of human eye is explored in this research. This concept is based on the vibration characteristics of the eye. The biomechanical eye model is described by the boundary value problem of small fluid-structure interaction oscillation superimposed on a static configuration state corresponding to the initial large deformation due to the IOP loading. Since the response of the eye is a function of the elasticity and IOP, it is essential that the elastic moduli are recovered simultaneously with the IOP to render the determination objective. To recover the IOP, an inverse problem is formulated by minimization of a multiple-frequency residual functional which quantifies the deviation of the predicted displacements from the signature profiles. These distinctively different dynamic deformations at multiple frequencies lead to the regularization of the ill-posed inverse problem. A gradient-based algorithm is employed for the minimization, and the sensitivities are calculated by the adjoint method. For the computation of the multiple-frequency solutions and the sensitivities at each functional evaluation step, a full-field matrix-Pade via Lanczos technique is developed and it allows for simultaneous computation of these displacements and adjoint fields with the cost of essentially one factorization. By comparison to the stretching stiffness, the prestress is concluded to be a higher-order term; and its effect on the residual functional is improved by using waveform excitation. Since the prestress is due to the IOP loading, it must be determined to render the problem tractable. A closed-form expression for the prestress function is obtained by using an asymptotic procedure for the corneoscleral shell. Several inversion results are reported. The elastic moduli are accurately recovered, and hence render the IOP an objective measure.
590 $a School code: 0212.
650 4 $a Applied Mechanics. $3 1018410
650 4 $a Engineering, Mechanical. $3 783786
690 $a 0346
690 $a 0548
710 2 0 $a Stanford University. $3 754827
773 0 $t Dissertation Abstracts International $g 67-09B.
790 $a 0212
790 1 0 $a Pinsky, Peter M., $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3235267