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Details
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Title: Identification of
dielectric target in a half-space using Complex Natural Resonance (CNR) method
Speaker: Dr Shantanu Padhi
Affiliation: EMI/CSSIP
Time: 1pm-1.30pm, Tuesday, 14th March
Venue: 78-420
Abstract: This presentation describes an approach to model the impulse
response of a dielectric target below a half space using the time domain
deconvolution technique. The complex natural resonances (CNR) of the target
are extracted from the time domain impulse response using a matrix pencil
method and can be correlated to the target’s physical properties. An automated
E-pulse scheme has been used to discriminate the change in physical properties
of target. The discrimination performance is calculated quantitatively by EDN and
DR. It is speculated that this technique can ultimately be used as a
diagnostic tool in detection and discrimination of target in conjunction with
other mammography techniques in detection
of cancerous tumours in tissue type
structure.
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Title:
Exploiting Ionospheric Errors in
Positioning Signals
Speaker: Dr Ildiko Horvarth
Affiliations: EMI, ITEE
Time: 1pm, Tuesday, 4th April
Venue: 78-420
Abstract: The ionosphere is a layer of fluid like plasma around the
Earth situated at around 100 km and above where free electrons exist in large
numbers. Although the ionosphere comprises less than 1% of the mass of the
upper atmosphere, it has a significant influence on advanced communication and
navigation systems like GPS and Gallileo. As today’s society begins to rely
more and more on complex technologies, these systems become increasingly
vulnerable to space environment effects. Space weather is the modern phrase
for these effects, and periods of high activity are called magnetic storms.
Magnetic storms can interrupt communications and may even cause catastrophic
power outages. In order to deal with the space-weather related technological
problems and difficulties, monitoring the daily variability of space weather,
specifying the various space weather features that create space weather, and
investigating the physical processes that drive space weather are important
experimental fields of space science, which is a developing discipline in
Australia.
Experimental research forms the basis of accurate modelling and reliable
forecasting. A good knowledge of the ionosphere is vital for modelling, and
both are now recognised as important components in defence technologies,
national security and safeguarding Australia. For instance, many of the
activities of the Australian Defence Force including communications,
surveillance, radar and intelligence gathering are supported by a significant
ionospheric modelling effort. This seminar will describe the various
space-weather related technological problems, and show some space weather
features detected by the ground-based GPS and space-based TOPEX/Poseidon
techniques. GPS signal degradations such as scintillation triggered by the
dynamic and stormy ionosphere will be demonstrated with some real-world
examples.
Finally, the possibility of improving existing models and current
forecasting/warning abilities in order to improve the performance of GPS in
various areas such as in location identification and communications will be
discussed.
Biography:
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Title: Detection of Depth
Changes of a Metallic Target Buried inside a Lossy Halfspace Using the E-Pulse
Technique
Speaker: Antony Lui
Affiliations: EMI
Time: 1pm, Tuesday, 11th April
Venue: 78-420
Abstract: The E-Pulse technique has been widely applied to the problem
of free space radar target identification. In this paper the possibility of
applying the same E-Pulse technique to a subsurface target recognition scheme
is investigated. In particular, the detection of depth changes of a metallic
target is considered with a numerical example that determines the depth of a
hip prosthesis model buried inside representative human tissue.
Biography: Hoi-Shun Lui is doing his PhD at the School of Information
Technology and Electrical Engineering under the supervision of A/Prof Nick
Shuley. He was born in Hong Kong and received his his Bachelor of Engineering
(Electrical) at the University of Queensland with the University Medal in
2003. He commenced his PhD at 2004. His research interest includes Resonance
Based Target Identification, Electromagnetic Scattering and Computational
Electromagnetics. |
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Title 1: A Simple Relationship
for High Efficiency-Gradient Uniformity Trade-offs in Multi-Layer Asymmetric
Gradient Coils
Title 2:Torque-Figure of Merit Trade-off in
Multi-Layer Asymmetric Gradient Coils
Speaker: Héctor Sánchez López
Affiliations: EMI, ITEE
Time: 1pm, Tuesday, 2nd May
Venue: 78-420
Abstract 1: In this work, we have studied the influence of DSV size,
coil length and radius, relative axial offset position of DSV and target
gradient field uniformity over the figure of merit in multi-layer asymmetric
transverse gradient coils. A simple linear function that defines the optimal
coil length to produce a maximum figure of merit given a DSV size, coil
radius, axial offset position and introduced uniformity error is obtained.
Applying the method and the linear functions derived, high quality solutions
are obtained.
Abstract 2: In the present research we describe the relationship
between the figure of merit and target torque minimization value for
multi-layer asymmetric transverse gradient coils taking into account the real
field profile of long and short bore symmetric and asymmetric magnets. Two
torque/force minimization strategies are introduced in order to obtain
asymmetric transverse gradient coils with a high minimum torque-maximum figure
of merit trade-off. Simple current pattern, minimum torque, high performance
head asymmetric gradient coils are obtained combining the real external
magnetic field effects over the gradient coil with a specific axial position
of the gradient coil’s DSV. |
Title:
Interactive medical image segmentation with haptic feedback
Speaker: Erik Vidholm
Affiliations: Centre for Image Analysis, Uppsala University, Sweden
Time: 1pm, Tuesday, 12th September
Venue: 78-411
Abstract: One of the most important steps in medical image analysis is
segmentation. Segmentation is needed in diagnostics, therapy monitoring,
surgery planning, and several other medical applications. Manual segmentation
of the structures of interest in medical datasets is very tedious and
error-prone. On the other hand, fully automatic segmentation is hard to
achieve. Consequently, many methods are semi-automatic, i.e., the segmentation
algorithm is provided with high-level knowledge from the user. The interactive
part is highly dependent on the user interface. Interfaces that rely on 2D
interaction have many drawbacks when the data is 3D. In our work, we use a
system that combines 3D input/output, stereo graphics, and haptic feedback to
facilitate 3D interaction. In this talk I will give an overview of our work in
this area. |
Title:
Receiving Mutual Impedance between Two Parallel Dipole Antennas
Speaker: Shiyang Lu
Affiliations: EMI, ITEE
Time: 2pm, Thursday, 9th November
Venue: 78-420
Abstract: The mutual coupling effect between antenna elements is one of
the critical problems in the application of antenna arrays. Traditionally, the
mutual impedance was used to measure the mutual coupling effect. In this
seminar, a new mutual impedance, the receiving mutual impedance, between two
parallel dipole antennas is introduced and defined rigorously. Its importance
and its differences from the conventional mutual impedance are fully
explained. The advantage of using the receiving mutual impedance over the
conventional mutual impedance is demonstrated through a direction-finding
problem.
Biography: Shiyang Lu graduated from Beijing University of Post &
Telecommunications, China and is now a MPhil student in the division of
Electromagnetics and Imaging of the School of ITEE. His research interest is
in multi-antenna and multi-carrier communication systems and array signal
processing. |
Title: MRI
Acoustic Noise and Vibration Reduction
Speaker: Chris K Mechefske
Affiliations:
Time: 2pm, Tuesday, 5th December
Venue: 78-420
Abstract: High speed switching of current in the gradient coils within
high magnetic field strength Magnetic Resonance Imaging (MRI) scanners
results in high acoustic sound pressure levels (SPL) in and around these
machines. This high level of acoustic noise generated during imaging
makes the process extremely uncomfortable and potentially hazardous
(short term and/or permanent hearing loss) for patients and clinical
technicians. Personal hearing protection devices provide some protection,
but limit easy communication between the clinicians and the patients. The
primary source of the acoustic noise is the vibration of the gradient
coil cylinder and other adjacent structures within the MRI. These
vibrations also cause reduced image quality by disturbing the radio
frequency coil that is used to detect imaging inputs.
The seminar will describe an overview of recent work to reduce vibrations
and the acoustic noise produced by these machines. Passive and active
vibration and acoustic reduction methods are being investigated. To
characterize the vibration properties as well as the acoustic noise
properties of the gradient coil Finite Element (FE) analysis, analytical
modeling and experimental methods have been employed. Models have been
developed using the dimensional specifications of a gradient coil insert
and the appropriate input current signals. These models have been
validated against one another and experimental results. The current work
is focusing on developing optimum vibration and acoustic design
constraints that can be used together with existing magnetic field and
imaging constraints to design quiet MRIs.
Biography: Chris K Mechefske is currently Associate Professor, Queen's
University, Kingston, Ontario, Canada and his research interests
include: Vibration Based Machine Condition Monitoring and Fault
Diagnostics, Pattern Recognition, Maintenance and Reliability, Machine
Dynamic Analysis, Biomechanics of Artificial Limbs, Vibration and Noise
Reduction in and around Biomedical Equipment. |
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Maintained: Andrew
Bradley
Last updated: 3-June-05
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