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Transcript
Physics Annual Symposium 2015/16
B.Sc. (Hons) Physics Project
Date:
Time:
Venue:
Wednesday, 4th May 2016
8.30 – 17.00
MP216
8.30 – 8.45
Introduction & Objectives of the Symposium
Head of Department: Professor CV Sammut
8.45 – 9.00
Student: Gabriel Falzon
Title: An Integrated system for Telescope Control using FPGAs
Chairman: Prof C V Sammut
Supervisor: Prof K Zarb Adami
Examiner: Dr A Magro
9.00 – 9.15
Student: Kevin Psaila
Title: f(R,T) Reconstruction Models in FLRW Cosmologies
Chairman: Prof C V Sammut
Supervisor: Dr J Said
Examiner: Prof K Zarb Adami
9.15 – 9.30
Student: Andrew Finch
Title: Gravitomagnetic Effects in Quadratic Gravity
Chairman: Prof C V Sammut
Supervisor: Dr J Said
Examiner: Prof K Zarb Adami
9.30 – 9.45
Student: Daphne Pollacco
Title: Measurement of Complex Permittivity of Sodium Chloride and Tissue mimicking
Solutions from 100MHz to 3GHz.
Chairman: Prof K Zarb Adami
Supervisor: Prof C V Sammut/Dr L Farrugia(co-supervisor)
Examiner: Dr L Zammit Mangion
9.45 – 10.00
Student: Jacob Spiteri
Title: Electrodynamic Levitation
Chairman: Prof C V Sammut
Supervisor: Dr L Zammit Mangion
Examiner: Dr A Xuereb
10.00 – 10.15
BREAK
1
10.15 - 10.30
Student: Melissa Caruana
Title: Entropy and Correlations in an Open Quantum System
Chairman: Prof C V Sammut
Supervisor: Dr A Xuereb
Examiner: Prof A Micallef
10.30 - 10.45
Student: Antonella Cutajar
Title: Development and Evaluation of a Simple Dispersion Model for an Atmospheric Point
Source
Chairman: Prof R Ellul
Supervisor: Prof A Micallef
Examiner: Dr P S Farrugia
10.45 – 11.00
Student: Nicolai Cumbo
Title: Investigating the Expansion of a Braided Interplanetary Magnetic Field
Chairman: Prof C V Sammut
Supervisor: Dr P S Farrugia
Examiner: Prof A Micallef
11.00 – 11.15
Student: Massimo Grech
Title: Dating a Large Tsunami Event on the Maltese Islands
Chairman: Dr G Debono
Supervisor: Dr A Micallef
Examiner: Dr P Galea
M.Sc. Project
11.15 -11.45
Student: Mark Pace
Title: Extreme Stars in Modified Gravity
Chairman: Professor CV Sammut
Examiner: Dr J Said
Examiner: Prof K Zarb Adami
2
B.Sc. (Hons) Short Review Paper and Seminar
14.00 - 14.15
Student: Massimo Grech
Title: Underwater landscapes of the central Mediterrenean Sea
Chairman: Dr P Galea
Supervisor: Dr A Micallef
Examiner: Prof A Drago
14.15 - 14.30
Student: Nicolai Cumbo
Title: The Inner Workings of Neutron Stars
Chairman: Prof C V Sammut
Supervisor: Dr J Said
Examiner: Prof K Zarb Adami
14.30 - 14.45
Student: Andrew Finch
Title: The Cosmic Microwave Background Radiation: Source and Anisotropy
Chairman: Professor C V Sammut
Supervisor: Dr J Said
Examiner: Prof K Zarb Adami
14.45 – 15.00
Student: Kevin Psaila
Title: Dark Energy
Chairman: Prof C V Sammut
Supervisor: Dr J Said
Examiner: Prof K Zarb Adami
15.00 – 15.15
Student: Jacob Spiteri
Title: Casimir-Polder Force and Casimir Friction
Chairman: Prof C V Sammut
Supervisor: Dr A Xuereb
Examiner: Dr P S Farrugia
15.15 - 15.30
Student: Gabriel Falzon
Title: Origins of “the Quantum Advantage”
Chairman: Prof C V Sammut
Supervisor: Dr A Xuereb
Examiner: Dr P S Farrugia
15.30 – 15.45
BREAK
15.45 – 16.00
Student: Melissa Caruana
Title: Observable Consequences of Quantum Statistics: from Cooper Pairs to Bell
Chairman: Prof C V Sammut
Supervisor: Dr A Xuereb
Examiner: Prof A Micallef
16.00 – 16.15
Student: Daphne A Pollacco
Title: Microwave Medical Imaging
3
Chairman: Prof A Micallef
Supervisor: Professor C V Sammut
Examiner: Dr L Zammit Mangion
16.15 – 16.30
Student: Antonella Cutajar
Title: The Physics of Urban Climatology
Chairman: Prof R Ellul
Supervisor: Professor A Micallef
Examiner: Dr P S Farrugia
16.30 – 16.45
Student: Anita Farrugia
Title: The Role of Hydrocarbons and other Volatile Organic Compounds in the Earth’s
Atmosphere
Chairman: Dr P S Farrugia
Supervisor: Prof R Ellul
Examiner: Dr A Galea
Closing
4
Abstracts
B.Sc. (Hons) Physics Project
Student: Gabriel Falzon
Title: An Integrated System for Telescope Control using FPGA(s)
Abstract: Astronomical radio interferometers typically consist of an array of antennas,
widely separated and connected using a transmission line. Signals recorded from each
antenna are sent to a back-end where they are digitized, channelized and superposed,
giving rise to constructive / destructive interference depending on whether the signals are
phased or not. This technique of interferometry is called aperture synthesis and it results
in a combined telescope, with a resolution equivalent to that of a single antenna with a
diameter equal to the spacing of the antennas furthest apart in the array. When we
consider a radio signal from a celestial source, incident on two antennas separated by a
distance, the antennas receive the radio signal with a time difference, causing the signals
to be out of phase. In order to achieve amplitude amplification, the recorded signals must
be phased using a technique called beamforming. A beamformer, has the added capability
of steering the beam of a radio telescope using constructive / destructive interference.
The aim of this project is to design and implement an integrated control system (ICS) for
the digital steering of beams in a radio telescope. The system will be implemented on the
ROACH2 FPGA board and will be capable of continually steering beams in the sky,
whilst monitoring the behavior of a phased array system to ensure that the beams are
continually tracking a source.
Student: Kevin Psaila
Title: f(R,T) Reconstruction Models in FLRW Cosmologies
Abstract: The concept of gravity is very important yet there is no complete description
on how this force actually works. It can be a manifestation of curvature in the geometry
of spacetime, as postulated by Einstein, or something else. Although the General
Relativity viewpoint turned out to be the most successful theory in describing gravity,
it is still an incomplete theory of gravity since it fails at explaining certain
phenomena that are currently being observed such as galactic rotation curves and the
accelerated expansion of the Universe in recent times. As a result cosmologists are trying
5
to find alternative theories of gravity that are consistent with the current
observations. f(R,T) modified theories of gravity will be investigate and by assuming that
the expansion history of the universe is known, field equations are inverted to get to
determine which modified theory gives a flat Friedmann−Robertson−Walker model.
Modified f(T) (where T is the trace of the energy-momentum tensor) models of gravity
will also be reviewed in order to obtain a new solution for the scale factor, Hubble
parameter and deceleration parameter in terms of the cosmic time.
A completely new toy model, that describes the cosmic evolution from 13.7 billion years
ago till the present time, will be proposed which is found to be consistent with dark
energy; something that the original theory of general relativity does not predict. This toy
model is further extended to examine the scale factor behavior in the nearby and distant
future so that the fate of the universe can be determined.
Student: Andrew Finch
Title: Gravitomagnetic Effects in Quadric Gravity
Abstract: In this presentation the concept of alternate theories of gravity will be briefly
discussed leading to the one used throughout my thesis, that of quadric gravity. A Kerrlike metric in quadric gravity for the vacuum space outside of a rotating, spherically
symmetric gravitational source will then be considered. The equations for Kepler’s third
law and two gravitomagnetic effects, the geodetic precession effect and the Lens Thirring
effect in quadric gravity will then be presented and compared to their general relativistic
counterparts. Finally results obtained from these equations when applied to a specific
system, that of a satellite orbiting the earth, will be presented and interpreted.
Student: Daphne A Pollacco
Title: Measurement of Complex Permittivity of Sodium Chloride and Tissue mimicking
Solutions from 100MHz to 3GHz.
Abstract: The aim of this work was to investigate the dielectric properties of solutions
which can be used to mimic the electrical properties of human breast tissues. By
analyzing the dielectric properties of tissue mimicking solutions, it is possible to
characterise the interaction of electromagnetic fields with the human body, the amount of
energy that the body absorbs and how much ionic currents are induced in the body.
Previous studies have used sodium chloride (NaCl) and Triton X-100 to approximate the
dispersive dielectric properties of a variety of human soft tissues from 500 MHz up
to 6GHz. Different tissues can be mimicked by a selection of the appropriate
concentration of NaCl and Triton X-100 solutions. In this study, measurements were
conducted on 21% TX-100, 28% TX-100 and 40% TX-100 in order to mimic different
percentages of adipose in breast tissues while extending current knowledge to
100MHz. Measurements were performed at 25 and 37 degrees Celsius. Prior to
conducting these measurements, a new, state-of-the-art probe (DAK) was validated by
conducting measurements on 0.1 N NaCl. The results were analysed and compared
to those published in the literature and then fitted to relaxation models. Most dielectric
6
parameters were observed as a function of frequency and temperature. Measurement
uncertainty analysis was also performed for both saline and Triton X-100 solutions.
These results contribute to further research in microwave diagnostic
and therapeutic applications in medical physics for safer and more reliable detection of
breast cancer as well as application in microwave hyperthermia.
Student: Jacob Spiteri
Title: Electrodynamic Levitation
Abstract: Magnetic levitation has been a topic of interest since the 19th century
electromagnetism boom, and still is today. There are many ways to achieve a controllable
lift using various electromagnetic methods. Up to a a couple of years ago the idea of
having a floating rideable personal 'hoverboard' was a Sci-Fi dream, immortalized by the
1989 movie 'Back to the Future Part II'. In November of 2014 a company from
California, U.S.A introduced a rideable floating 'Hoverboard' using maglev technology as
a 'Kickstarter' project. Following an overview of various magnetic levitation
technologies, this work focuses solely on electrodynamic levitation. Computer
simulations and experimental measurements were performed for two methods, using ac
induction from a coil and using a system of rotating permanent magnets similar to that
used in the Hoverboard.
Student: Melissa Caruana
Title: Entropy and Correlations in an Open Quantum System
Abstract: An open quantum system, as the name suggests, is a quantum-mechanical
system which interacts with the rest of the universe. We will start by looking
at Landauer's principle and its relation with the second law of thermodynamics and with
information. This thesis will then look at the correlations, heat exchanged and entropy of
a simple open quantum system that interacts with its environment as we tune this
interaction from a simple Markovian one, which is an interaction that does not maintain a
memory of the past to one that is increasingly non Markovian.
Student: Antonella Cutajar
Title: Development and Evaluation of a Simple Dispersion Model for an Atmospheric
Point Source
Abstract: Atmospheric dispersion modelling is an essential tool for studying the effects
of air pollution and is very frequently used to set regulations for the introduction of new
sources of pollution in the environment. In this project, a simple Gaussian dispersion
model is developed to study the dispersion of a plume from a stack. Three versions of the
model are created; in each one a different formulation is used to calculate the horizontal
and vertical dispersion coefficients. The model is then evaluated using the Thompson
wind tunnel data – a data set collected from experiments carried out in the U.S.
Environmental Protection Agency wind tunnel. Validation is made through linear
regression and statistical analysis. Results show that the model slightly underestimates
pollutant concentration as the plume is modelled to disperse much quicker than it does in
reality; however there is a fair linear correlation between the observed data and the
7
predicted values. A relation between height of stack and model performance is also
observed. Finally, some modifications to the horizontal dispersion parameters are
implemented using curve fitting techniques. Such modifications indeed show an
improvement in the results output by the model.
Student: Nicolai Cumbo
Title: Investigating the Expansion of a Braided Interplanetary Magnetic Field.
Abstract: Plasma motion in the Sun creates a persistent magnetic field that extends
outwardly as far as Pluto and beyond. Assuming a steady state system, this so called
interplanetary magnetic field takes the shape of an Archimedes spiral, known as the
Parker spiral. However, the outer layers of the Sun are evolving continuously creating
fluctuations in the magnetic field lines. These braid the magnetic field lines making its
representation much more complicated.
As the magnetic field lines move outwardly from the Sun, the separation between them
increases. This affects the transport properties of fast moving particles, called solar
energetic particles, which are emitted from the sun. Such particles are of interest not only
because they are a health hazard in outer space, but also because they can be used to
probe the magnetic turbulence of outer space. Thus, it is important to account for the
expansion of the magnetic field lines when calculating their transport properties.
While an analytical model for the expansion of the Parker spiral in terms of area
enclosing a fixed amount of flux is readily derived, that for a braided magnetic field
could not be obtained so easily. In this context, the research uses numerical techniques in
order to investigate the evolution of a braided field line. It then builds on the result to
determine how the area enclosing a fixed amount of flux in such a field changes with
radial distance from the Sun.
Student: Massimo Grech
Title: Dating a Large Tsunami Event on the Maltese Islands
Abstract: The Maltese Islands have been subject to numerous tsunamis in the past, some
of which were strong enough to modify the shape of our coastlines. Various historians
describe an earthquake in 1693, which resulted in a tsunami that affected Xlendi, where
the sea “rolled out to 1 mile and swept back a little later”. Another tsunami was triggered
by the 1908 Messina earthquake, although this had limited impact on the Maltese
archipelago, such as localised flooding and minor strucural damage. On the north-eastern
coasts of Malta several erosional forms including 70-ton boulders and 11 m by 6 m large
socket forms can be found. A recent study by Mottershead et al. (2014) investigated
geomorphic signatures at Ahrax and other coastal sites to propose that a 20 m tsunami
wave affected the eastern coastline of the Maltese Islands. The objective of this
8
dissertation is to test the validity of this hypothesis by analysing the nature and
distribution of sediments along the Ahrax coast and explain the latter using
hydrodynamic equations. An attempt is also made to estimate the age of the tsunami
event.
M.Sc. Project
Student: Mark Pace
Title: Extreme Stars in Modified Gravity
Abstract: Neutron stars represent the extreme regime where gravitational and particle
physics meet. They suffer the intense inward pressure of gravity and, at the same time, a
large outer pressure due to the interactions of the particles pressure. These 10 km radius
stars are under such intense pressures that all the atoms present have broken down into
their constituent components. Computer simulations will be used to compute the
differences that competing theories of gravity produce in terms of this strong end of the
region. Up to this point in time such research has mostly been done using Einstein’s
theory of gravity, general relativity, however a growing number of researchers are
starting to use this as a test of modification to this model in order to better explain some
of its shortcomings. Theories based upon the curvature scalar have been extensively
studied, however new up and coming theories have been emerging where instead of the
curvature scalar, we base our theories on the torsion of the space-time through the
Weitzenbock connection, called f(T). Such a theory however does not take into account
the aspect where the cosmological constant may be a variable, which may depend on the
trace of the energy-momentum tensor, T . Thus giving rise to the f(T, T ) theory of
gravity. f(T, T ) theory of gravity is a more general form of f(T) theory. This project’s
goal is to apply such a theory to extreme stars, and attempt to derive the governing
equation; Tolman Oppenheimer Volkoff (TOV) equation. Having such an equation then
allows us to study the mass-radius relation of the neutron star within a certain strong field
gravity. 1
B.Sc. (Hons) Short Review Paper
Student: Massimo Grech
Title: Underwater landscapes of the central Mediterranean Sea
Abstract: Although the surface layers of the Mediterranean are generally well known to
many, some of its deeper layers remain a mystery. This is mainly due to the difficulties
encountered in order to investigate at these depths, which can be predominantly done
using geophysical instruments. The objective of this study is to shed light on the
underwater landscapes of the central Mediterranean and what we know about them up till
9
now. These include the Malta-Sicily Escarpment (MSE), the Ionian Abyssal Plain (IAP),
the Malta Plateau, the Malta Graben, and the Gela Basin. A discussion of the submerged
terrestrial landscapes of the Maltese Islands is also given. With sea levels rising, the
general interest in underwater landscapes and their exploration is also expected to
increase in the future.
Student: Nicolai Cumbo
Title: The Inner Workings of Neutron Stars.
Abstract: The state of the matter at the core of Neutron Stars remains uncertain to this
day. However, models based on theoretical possibilities have been formed, and compared
to observational data where possible. These models depend highly on the equation of
state (EOS), which is a relation between the pressure of the matter present and
the density. In this presentation, the EOS of the outer core of Neutron Stars is reviewed,
followed by the simplest form for the inner core. Next, several 'exotic' phases of matter
are reviewed, and their effect on the EOS explained.
Student: Andrew Finch
Title: The Cosmic Microwave Background Radiation: Source and Anisotropy
Abstract: In this presentation the origin and the mapping of the cosmic microwave
background radiation (CMB) and its anisotropies will be considered including an
overview of the three space missions dedicated to this task. Finally the significance of the
CMB and its anisotropies along with their contribution to modern cosmology will be
outlined.
Student: Kevin Psaila
Title: Dark Energy
Abstract: Relatively recent observations have confirmed that around 70% of the
Universe is made up of dark energy which is the key component for the current cosmic
accelerated expansion. In this paper, present observational evidence and theoretical
models that have been proposed in trying to explain dark energy and its negative pressure
under the important assumption of a flat Universe are reviewed. Various probes of dark
energy including baryon acoustic oscillations, Supernovae type Ia and weak gravitational
lensing will be discussed. The two leading theoretical models, the cosmological constant
model and the quintessence model, will also be reviewed together with the fine tuning
and coincidence problems. The "tracking" solution will also be introduced as an
explanation for the fact that the energy densities of matter and vacuum energy are of the
same order at approximately the present time.
Student: Jacob Spiteri
10
Title: Casimir-Polder Force and Casimir Friction
Abstract: 69 years ago in 1947, two Dutch physicists named Hendrik Casimir and Dirk
Polder theorized the existence of an attractive force between two neutral atoms, and
between an atom and a conducting plate, this is known as the Casimir-Polder force. A
year later Casimir formulated the force between two neutral conducting plates in a
vacuum, this is generally known as the Casimir Effect. Since then the notion of
quantum/Casimir friction has come up, this phenomenon entails this Casimir-Polder type
force on a moving atom causing a dissipative quantum electrodynamic force, i.e. a
friction like force. Theorists have tried to describe and quantify this force for more than 3
decades now. This review gives an overview of what has been done up to now with
regards to theory and experimental work on this minute force.
Student: Gabriel Falzon
Title: Origins of “the Quantum Advantage”
Abstract: Quantum information theory predicts that certain algorithms undergo speedup when implemented on quantum machines, making them more efficient than classical
implementations. This review presents a qualitative description of this increased
efficiency, termed `quantum advantage', by defining computational complexity and
investigating Shor's and Grover's quantum algorithms. Among the proposed sources of
this quantum advantage is the non-local correlation known as entanglement. This review,
explores how entanglement is an essential resource for pure-state quantum algorithms but
not a necessity for quantum algorithms operating on mixed-states. Efficiencies achieved
by mixed-state quantum computations force the introduction of a concept known as
discord and an investigation of how it came to be considered a resource for the mixedstate DQC1 model. A discussion on the role of entanglement and discord, as resources for
the quantum advantage in quantum computation and communication, presents significant
arguments to the open question about the origin of the quantum advantage.
Student: Melissa Caruana
Title: Observable Consequences of Quantum Statistics: From Cooper Pairs to Bell
Abstract: The elementary particles that make up ordinary matter are bosons and
fermions which obey different statistics. There are other particles such as anyons which
are neither bosons nor fermions, but somewhere in between and obey another type of
statistics. In what follows, we will give a brief description of bosons and fermions and go
into detail about anyons, their statistics and the phenomena they lead to. The difference
between
classical
and
quantum
statistics
will
then
be
discussed
using Heisenberg's Uncertainty Principle and arguments from the famous EPR paper and
Bell's Theorem.
11
Student: Daphne A Pollacco
Title: Microwave Medical Imaging
Abstract: This paper reviews microwave imaging techniques used in the screening for
and diagnosis of tumours, with special reference to breast cancer. There are various
microwave imaging techniques which can be used to diagnose cancer and these can be
classified into three modalities. These are: hybrid microwave induced acoustic
imaging techniques, ultra-wide band radar based imaging and microwave
tomography. Out of these three modalities, the ultra-wide band microwave (UWB)
imaging technique is a particularly popular, emerging new field of research. Currently,
mammography is the most prevalent screening method in most medical institutions.
However it has its disadvantages. Ituses ionising radiation, it is highly
uncomfortable because it involves compression of the breast while offering low
resolution images. The UWB technique, on the other hand, utilizes non-ionizing radiation
and eliminates the discomfort of breast compression. However, the sensitivity and the
possibility of differentiating between benign and malignant tumours is still highly
debatable in this field of research. This paper reviews past, current and future potential
use of microwave imaging methods, the fundamental principles in physics dominating
this new field of research and the mathematical analysis that goes along with interpreting
the results obtained through microwave imaging. Research in microwave medical
imaging is still being carried out till this day and it is still debatable whether this
technique will take over current imaging modalities.
Student: Antonella Cutajar
Title: The Physics of Urban Climatology
Abstract: With the rapid increase in the number of urban dwellers, the study of urban
climatology has become increasingly important over the last few decades. The
development of urban settlements and the activities cities bring with them lead to the
creation of microclimates. The main parameters that are modified in these newly created
microclimates include: the atmospheric composition, the heat budget, wind speed and
humidity. In this review paper, the processes by which these modifications arise are
studied and the effects of such modified microclimates are also outlined. Some
precautions that should be taken while developing cities to help minimise the culprits of
urbanisation are also mentioned.
Student: Anita P Farrugia
12
Title: The role of Hydrocarbons and other Volatile organic compounds in the Earth’s
atmosphere
Abstract: Hydrocarbons and other volatile organic compounds (VOCs) are abundant in
sources and a cause of several detrimental health and environmental effects. Their
presence in both indoor and outdoor environments is a result of both anthropogenic and
biogenic activity, this means that they are near impossible to escape, with concentrations
varying depending on population sizes, urban and industrial activity. This review aims to
discuss the sources of these VOCs present in the atmosphere as well as their resulting
effects on both human health and the environment.
Student: Massimo Grech
Title: Underwater landscapes of the central Mediterranean Sea
Abstract: Although the surface layers of the Mediterranean are generally well known to
many, some of its deeper layers remain a mystery. This is mainly due to the difficulties
encountered in order to investigate at these depths, which can be predominantly done
using geophysical instruments. The objective of this study is to shed light on the
underwater landscapes of the central Mediterranean and what we know about them up till
now. These include the Malta-Sicily Escarpment (MSE), the Ionian Abyssal Plain (IAP),
the Malta Plateau, the Malta Graben, and the Gela Basin. A discussion of the submerged
terrestrial landscapes of the Maltese Islands is also given. With sea levels rising, the
general interest in underwater landscapes and their exploration is also expected to
increase in the future.
13