<p> This thesis contributes significantly to the advanced electromagnetic (EM) modeling
of the interaction of the microwave field with human tissues. The proposed EM
models achieve unprecedented computational efficiency, accuracy, and reliability. </p> <p> The EM modeling is crucial in (a) multiphysics and (b) EM analysis m
support of optimization procedures with applications in design optimization and
inverse problem solutions. The challenge in such applications stems from the fact
that EM modeling requires extensive computational resources. Therefore, the
reduction of these computational requirements is necessary in order to handle the
complexity of multi physics modeling and microwave imaging. </p> <p> In this thesis, an efficient EM/thermal analysis of the interaction of the radiofield
(RF) fields of mobile phones with the human eyes is presented. Another
advanced application developed here is the solution of inverse problem in microwave
imaging and detection by making use of response sensitivity analysis. </p> <p> Two methods are proposed for the evaluation of the maximum specific
absorption rate (SAR) in the human eyes due to RF exposure from handheld devices.
They account for the existence of resonance in the eye and are applied to the case of near-field exposure. The first method is semi-analytical. As an input. it requires the
measured or simulated open-space near field of the device under test in the absence
of the eye. As an output. depending on the mutual position and orientation of the eye
and the device, it produces the maximum SAR value in the eye averaged over I and
I 0 grams of tissue. The second method is experimental. It requires the fabrication of
a simple eye phantom and relies on a measurement with an SAR robot. The proposed
methods allow for the fast and reliable SAR evaluation of newly developed handheld
devices in an industrial environment. Results concerning the temperature rise in the
eyes are also presented. They are based on detailed simulation eye models. </p> <p> A conceptually new detection algorithm is proposed in this thesis for the
localization of electrically small scatterers in a known background medium. The
algorithm requires the knowledge of the electric field distribution inside the known
background medium where no scatterers are present. It is based on a self-adjoint
response sensitivity computation which can be performed in real time. Using the Efield
distribution in the background medium. it provides three-dimensional maps of
the Frechet derivative within the imaged volume. The peaks and dips in these maps
identify the locations where the permittivity and conductivity of the measured
medium differ from those in the background medium. The background medium can
be heterogeneous. The performance of the detection algorithm is studied in terms of
the number of transmission/reception points, the dielectric contrast of the scatterer
compared to the background medium, and the size of the scatterer. Its resolution is also addressed. The proposed detection algorithm is successfully applied in breast
cancer detection. </p> / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19028 |
| Date | January 2010 |
| Creators | Liu, Li |
| Contributors | Nikolova, N. K., Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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