RECONSTRUCTION OF PERMITTIVITY AND CONDUCTIVITY PROFILES OF A DIELECTRIC SLAB IN THE TIME DOMAIN BY DESCENT METHODS

Date

1992-10-01

Author

ONDER, M
Kuzuoğlu, Mustafa

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

211
views

0
downloads

An optimisation approach is presented for the problem of reconstructing the permittivity and conductivity profiles of a dielectric slab from the reflected and transmitted field data. The problem is treated as an optimal control problem where the norm of the difference of measured and calculated boundary data is minimised subject to the state equation governing the system. The original constrained optimisation problem is reduced to the evaluation of stationary points of an augmented functional which is obtained by the method of Lagrange multipliers. To find the necessary conditions for optimality, a variational approach is used which leads to a coupled system of four equations. The first two of these are differential equations named as state and costate equations, and the remaining two expressions are obtained by equating the gradients of the augmented functional, with respect to the permittivity and conductivity, to zero. Profile reconstruction is carried out by descent methods. At every iteration the state and costate equations are solved by the time domain finite element method. New estimates for the permittivity and conductivity profiles are obtained by a one dimensional search in a suitable descent direction.

Subject Keywords

General Engineering

URI

https://hdl.handle.net/11511/41535

Journal

IEE PROCEEDINGS-H MICROWAVES ANTENNAS AND PROPAGATION

DOI

https://doi.org/10.1049/ip-h-2.1992.0077

Collections

Department of Electrical and Electronics Engineering, Article

Suggestions

OpenMETU
Core

A computational procedure for estimating residual stresses and secondary plastic flow limits in nonlinearly strain hardening rotating shafts Eraslan, Ahmet Nedim (Springer Science and Business Media LLC, 2005-03-01) A computational procedure to estimate the residual stress distributions and the limit angular speeds for avoiding secondary plastic deformation in nonlinearly strain hardening rotating elastic-plastic shafts is given. The model is based on von Mises yield condition, J(2) deformation theory and a Swift-type hardening law. The boundary value problem for the governing nonlinear differential equation is solved by a shooting method using Newton iterations with numerically approximated tangent. Solid as well as h...
Kinetic analysis of DSC and thermogravimetric data on combustion of lignite Kök, Mustafa Verşan (Springer Science and Business Media LLC, 1996-06-01) Thermal analysis increasingly being used to obtain kinetic data relating to sample decomposition. This work involves a comparative study of several methods used to analyse DSC and TG/DTG data obtained on the oxidation of Beypazari lignite. A general computer program was developed and the methods are compared with regard to their accuracy and the ease of interpretation of the kinetics of thermal decomposition. For this study, the ratio method was regarded as the preferred method, because it permits the estim...
Yielding of two-layer shrink-fitted composite tubes subject to radial pressure Eraslan, Ahmet Nedim (Springer Science and Business Media LLC, 2005-12-01) Yielding of two-layer shrink-fitted composite tubes with axially constrained ends subject to either internal or external pressure is investigated in detail. In the framework of small deformations, a state of plane strain and von Mises yield criterion, analytical expressions are obtained for critical values of the pressure leading to plastic flow. It is shown that, depending on material properties and tube dimensions, different modes of plastic deformation may occur. Yielding may commence at the inner tube o...
Fabrication and characterization of p-Si/n-ZnO heterostructured junctions Klason, P.; Rahman, M. M.; Hu, Q. -H.; Nur, O.; Turan, Raşit; Willander, M. (Elsevier BV, 2009-04-01) In this paper ZnO nanorods and nanodots (with and without a SiO2 buffer layer) were grown on p-Si, forming p-n heterojunctions. The nanorod devices showed no visible electroluminescence (EL) emission but showed rectifying behavior. Covering around 60% of the length of the nanorods with PMMA produced an ideality factor of 3.91 +/- 0.11 together with a reverse saturation current of 6.53 +/- 4.2 x 10(-8) A. Up to two orders of magnitude rectification was observed for the current at bias -3 and 3 V. The nanodot...
Assessment of a frequency-domain linearised Euler solver for turbofan aft radiation predictions and comparison with measurements Özyörük, Yusuf (2010-03-31) This paper presents a frequency-domain computational aeroacoustics tool for predicting aft noise radiation through turbofan ducts and jets and its application to two realistic engine exhaust configurations which have been experimentally tested. The tool is based on the discretised axisymmetric form of the linearised Euler equations in conjunction with perfectly matched layer equations at the inlet and far-field boundaries using high-order finite differences. The resultant linear system of equations is inver...

Citation Formats

M. ONDER and M. Kuzuoğlu, “RECONSTRUCTION OF PERMITTIVITY AND CONDUCTIVITY PROFILES OF A DIELECTRIC SLAB IN THE TIME DOMAIN BY DESCENT METHODS,” IEE PROCEEDINGS-H MICROWAVES ANTENNAS AND PROPAGATION, pp. 435–440, 1992, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/41535.