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Novel methods for multi-target tracking with applications in sensor registration and fusion
Get PDFMaintaining surveillance over vast volumes of space is an increasingly important
capability for the defence industry. A clearer and more accurate picture of a surveillance region could be obtained through sensor fusion between a network of sensors.
However, this accurate picture is dependent on the sensor registration being resolved. Any inaccuracies in sensor location or orientation can manifest themselves
into the sensor measurements that are used in the fusion process, and lead to poor
target tracking performance. Solutions previously proposed in the literature for the
sensor registration problem have been based on a number of assumptions that do
not always hold in practice, such as having a synchronous network and having small,
static registration errors. This thesis will propose a number of solutions to resolving
the sensor registration and sensor fusion problems jointly in an efficient manner.
The assumptions made in previous works will be loosened or removed, making the
solutions more applicable to problems that we are likely to see in practice. The
proposed methods will be applied to both simulated data, and a segment of data
taken from a live trial in the field
What impact does the workplace culture of public sector institutions have on the career progression of Black employees?
Get PDFThis thesis explores the impact of workplace culture in public sector institutions on the career
progression experiences of Black employees. Constructivist grounded theory methodology,
which includes reflexivity and co-production, was used, with Critical Race Theory as a
sensitising lens. This research contributes to theory based upon three pillars: the intersection of
Human Resource Management with Equality and Diversity practice, the lived experience of
Black employees and the relationship between race and career progression.
The findings show that organisations create a segregated and racialised career experience for
Black employees, driven by anti-Black racism and Whiteness, which creates a two-tier
employee experience and holds back their careers. Organisational exclusion from corporate
talent management and succession planning occurred due to a disregard and lack of interest in
the careers of Black employees. HR Managers lacked the diversity and inclusion expertise
required to address racial discrimination in career progression and contributed to poor HR
policy and practice outcomes for Black employees.
The study revealed that race is the dominant factor that shapes the careers of Black employees
and hasresulted in an ethnicity career progression gap and racialised workplace cultures. Racial
discrimination was an accepted part of organisational culture and Black employees faced
sanctions for challenging discrimination. Consequently, this research reveals a chasm between
organisationally espoused commitments to racial diversity and the lived experience of Black
employees, which has far-reaching implications for achieving racial equality in the workplace.
This research posits that practice improvement in career progression for Black employees must
centre their lived experience and that not adopting this approach prohibits organisations from
achieving racial diversity at senior levels
Design, characterisation and testing of SU8 polymer based electrothermal microgrippers
Get PDFMicroassembly systems are designed to combine micro-component parts with high
accuracy. These micro-components are fabricated using different manufacturing
processes in sizes of several micrometers. This technology is essential to produce
miniaturised devices and equipment, especially those built from parts requiring different
fabrication procedures. The most important task in microassembly systems is the
manipulator, which should have the ability to handle and control micro-particles.
Different techniques have been developed to carry out this task depending on the
application, required accuracy, and cost. In this thesis, the most common methods are
identified and briefly presented, and some advantages and disadvantages are outlined.
A microgripper is the most important device utilized to handle micro-objects with
high accuracy. However, it is a device that can be used only in sequential microassembly
techniques. It has the potential to become the most important tool in the field of micro-robotics, research and development, and assembly of parts with custom requirements.
Different actuation mechanisms are employed to design microgrippers such as
electromagnetic force, electrostatic force, piezoelectric effect, and electrothermal
expansions. Also, different materials are used to fabricate these microgrippers, for
example metals, silicon, and polymers such as SU-8.
To investigate the limitation and disadvantages of the conventional SU-8
electrothermal based microgrippers, different devices designed and fabricated at IMT,
Romania, were studied. The results of these tests showed a small end-effector
displacement and short cycling on/off (lifetime). In addition, the actuator part of these
microgrippers was deformed after each operation, which results in reduced displacement
and inconsistent openings at off state every time it was operated in a power ON/OFF
cycle. One of these limitations was caused by the existence of conductors in arms of the
end-effectors. These conductor designs have two disadvantages: firstly, it raises
temperature in the arms and causing an expansion in the opposite direction of the desired
displacement. Secondly, since the conductors pass through the hinges, they should be
designed wide enough to reduce the conductor resistance as much as possible. Therefore,
the wider the hinges are, the higher the in-plane stiffness and the less out of plane
deflection. As a result, it increases the reaction force of the arm reducing the effect of
deformation. Based on these limitations a new actuatorstructure of L-shape was proposed to reduce
the effects of these drawbacks. This actuator has no conductor in the hinges or the arms
of the end-effectors which reduce limitation on the hinge width. . In addition, a further
development of this actuator was proposed to increase the stiffness of the actuator by
doubling its thickness compared with the other parts of the griper. The results of this
actuator proved the improvement in performance and reduction of the actuator
deformation.
This new actuator structure was used to design several different microgrippers with
large displacement and suitable for a wide range of applications. Demonstrations of the
capabilities of the microgrippers to be used in microassembly are presented.
In addition, a novel tri-directional microactuator is proposed in this thesis. This
actuator’s end-effector is capable of displacements in three different directions. This
actuator was used with the other designs to develop a novel three-arm (three fingers)
multidirectional microgripper.
To study the microgripper displacement as a function to the heater temperature, the
TCR of the conductor layer of each device was measured. Because different
configurations of conductor layers were studied, a significant effect of the metal layer
structure on TCR was discovered. The TCR value of gold film is reduced significantly
by adding the chromium layers below and about it which were used to improve the
adhesion between the gold film and the SU layers.
In this thesis, a new method based on a robotic system was developed to characterise
these microgrippers and to study the steady state, dynamic response, and reliability
(lifetime cycling on/off). An electronic interface was developed and integrated to the
robotic system to control and drive the microgrippers. This new system was necessary to
carry out automated testing of the microgrippers with accurate and reliable results.
Four different new groups of microgrippers were designed and studied. The first
group was indirectly actuated using an L-Shaped actuator and two different actuator
widths. The initial opening was 120 μm for both designs. The maximum displacement
was about 140 μm for both designs. However, the actuator in the wider heater width
showed more stable behavior during the cycling and the dynamic tests.
The second group was based on direct actuation approach using the L-Shaped
actuator. There were eight different designs based on this method with different heater
conductor shape, actuator width, and arm thickness. The initial opening was 100 μm and there were different displacements for the eight designs. The study of these microgrippers
proved that the actuator stiffness has a significant effect on the microgripper
displacement. In addition, the shape of the heater conductor has less effect. The largest
displacement achieved using this method of design was about 70 μm.
The third group was designed for dual mode operation and has three different designs.
The initial openings were 90 μm and 250 μm. The displacement was about 170 μm in
both modes. The last microgripper design was a tri-arm design for multi-mode operation.
The lifetime study of SU8 based microgrippers in this thesis was the first time such
an investigation was carried out. The results of IMT designs showed that the larger is the
displacement the less stable is the gripper design because of the high rection force acting
on the actuators. The L-shape based microgrippers had better performance and they did
not break after more than 400 cycles. In addition, the studies of static displacement and
dynamic response of different designed microgripper proved that better performance of
the proposed actuator can be obtained by using double thickness for the actuator as
compared to the arm thickness
Development of a broadband visible to infrared astrocomb
Get PDFMotivated by the applications of high-resolution spectroscopy in astrophotonics, this
thesis presents the experimental work and development of a broadband wide-mode-spacing astrocomb system as part of the UK consortium for the High Resolution
Spectrograph (HIRES) in the forthcoming Extremely Large Telescope (ELT).
A 1-GHz Ti:sapphire laser served as the master source comb of the system,
pumping a visible broadband supercontinuum and a phase-coherent PPKTP-based
degenerate optical parametric oscillator (OPO), spectrally broadened in highly non-linear fibre. The system was fully stabilised, and provided an atomically-traceable
1-GHz astrocomb across nearly two octaves from 500–2200 nm.
Residual noise from the dither-locked OPO hindered subsequent modal filtering
in a Fabry Perot cavity motivating development of a dither-free technique exploiting the always-present parasitic sum-frequency light. This locking protocol provided
a sixfold lower relative intensity noise and nearly five times less power fluctuation
than the dither-locked version, leading to successful modal filtering from 1150–1800
nm. The spectra of the filtered output were recovered using Fourier transform spectroscopy, with the 10-GHz comb mode spacings directly resolved optically. Through
linear regression, fCEO was found to be 565.7 MHz ± 64.3 MHz and frep was calculated as 992.1 MHz ± 352 Hz. Individual comb mode values were identified with
high accuracy using the comb equation. This technique was verified with a heterdyne experiment between the Ti:sapphire comb source and a Rb-referenced CW
laser to which the FTS was referenced.
An alternative approach for visible wavelength generation was investigated using
a PPLN waveguide. Using a sample optimised for 1560 nm, 1.5 % of our coupled
degenerate OPO input was up-converted to second harmonic generation as well as
sum-frequency mixing and showed a good agreement with modelled results, providing confidence in the ability to use such simulations to design fully grating-engineered
PPLN waveguide for broadband conversion
Mathematical modelling of corneal epithelium maintenance and recovery
Get PDFThe cornea is the clear shield that covers the eye, estimated to contribute approximately two thirds of the eye’s optical power. Therefore, cornea protection is highly important and is achieved by maintaining its outermost layer, the corneal epithelium. Corneal
epithelium maintenance depends on a peripheral population of stem cells, the limbal stem
cells, that continuously replenish the basal epithelium layer through generating transient
amplifying cells (TAC). TACs move from the periphery to the centre, undergoing several
rounds of cell division, before terminal differentiation (TD). TD cells lose contact with
the basal layer and move up through the epithelium until shed from the surface. A better
understanding of corneal epithelium maintenance and recovery processes are crucial and
may contribute to better treatments.
We develop and analyse mathematical models to investigate these underlying complex biological processes with the aim of a better understanding and possibly prediction
of what cannot be currently obtained from laboratories and clinical trials. The proliferation events are modeled by a stochastic mathematical model, based on an analogy
to chemical reactions. Using this model we are aiming to: (i) clarify the main factors
involved in the maintaining process; (ii) determine the constraints placed on the proliferation process for healthy maintenance; (iii) investigate robustness via noise analysis.
We then consider the spatial migration of TACs from the corneal epithelium periphery
to the centre. In the absence of no precise biological data on the exact mechanism governing centripetal migration of TAC cells, we consider two simple prototype models: (i)
TACs simply migrate randomly, i.e. a diffusion type process; (ii) random migration with
a centrally-directed bias, i.e. a diffusion-advection type process. We first use a first passage time approach to understand the constraints on the parameters for TAC cells to reach
the corneal epithelial centre and then investigate prototypical models to investigate the
mechanisms that account for TAC cell redistribution from the periphery to the centre. Behaviour of the models is investigated under wound healing scenarios, exploring whether
different healing is observed according to model and position of the wound.Engineering and Physical Sciences Research Council (EPSRC) grant EP/L016508/01Scottish Funding Counci
Learning to use data analytics to manage an outsourced public service : a case study of organizational learning
Get PDFPublic service outsourcing has been a decades-long practice of governments intent
on downsizing and leveraging private enterprise to realize market efficiencies.
The practice has delivered challenges for public managers, a key one being
detecting and managing opportunism, service provider advantage-seeking
behaviour. Outsourcing challenges may be met with the emerging potential of data
analytics, but to realize the potential, an organization is faced with learning how
to use data, analysis and scientific methods so that an orientation for evidence based management becomes an organizational norm. In this thesis the literature
from outsourced service management, the phenomenon of opportunism, data
analytics and organizational learning is examined to synthesize significant
findings and validate exploring the research question: When data analytics is
introduced to manage opportunism and accountability for an outsourced public
service, in what ways does the organization learn to use data and analytical
methods for performance management? The research was designed using the
foundational tenets of qualitative research, involving participants in an action
research case study. Through prolonged, longitudinal engagement the case
delivered the experience of a learning journey using the interview as purposeful
conversation. The research was designed in three phases to implement technology
and processes for data analytics in a public registry service outsourced to a
network of providers, then support the organization to develop familiarity with
using analytics, and finally evaluate the learning journey. This study shows that
pressure from authoritative sources in the government and enthusiasm for the
public service value of accountability led to accelerated learning to work in new
ways with data and analytics to manage service provider performance. But the
outsourced environment, and more particularly the business environment played
critical roles to limit learning and shift the focus from new ways of working to
exploiting existing ways and to mire the perceived problems of the organization
as top-of-mind for many. This study underscores how complex and fraught with
barriers a learning journey is and supplies lessons on organizational learning for
academics and practitioners. The study adds depth and nuance to the value of the
learning lens, where learning was an outcome from a study of learning
Modelling of capillary end effects in systems of variable wettability
Get PDFAbstract unavailable due to technical reasons. Abstract available in PDF
The relevance of prediction markets for corporate forecasting
Get PDFPrediction markets (PMs) are virtual stock markets on which shares are traded taking
advantage of the wisdom-of-crowds principle to access collective intelligence. It is
claimed that the accumulation of information by groups leads to joint group decisions
often better than individual participants’ approaches to solutions. A PM share represents
a future event or a market condition (e.g. expected sales figures of a product for a specific
month) and provides forecasts via its price which is interpreted as the probability of the
event occurring. PMs can be used in competition with other forecasting tools; when
applied for forecasting purposes within a company they are called corporate prediction
markets (CPMs). Despite great praise in the (academic) literature for the use of PMs as
an efficient instrument for bringing together scattered information and opinions,
corporate usage and applications are limited.
This research was directed towards an examination of this discrepancy by means of
focusing on the barriers to adoption within enterprises. Literature and reality diverged
and neglected the important aspect of corporate culture. Screening existing research and
interviews with business executives and corporate planners revealed challenges of
company hierarchy as an inhibitor to the acceptance of CPM outcomes.
Findings from 55 interviews and a thematic analysis of the literature exposed that CPMs
are useful but rarely used. Their lack of use arises from senior executives’ perception of
the organisational hierarchy being taxed and fear of losing power as CPMs (can) include
lower rungs of the corporate ladder in decision-making processes. If these challenges can
be overcome the potential of CPMs can be released. It emerged – buttressed by ten
additional interviews – that CPMs would be worthwhile for company forecasting,
particularly supporting innovation management which would allow idea markets (as an
embodiment of CPMs) to excel.
A contribution of this research lies in its additions to the PM literature, explaining the
lack of adoption of CPMs despite their apparent benefits and making a case for the
incorporation of CPMs as a forecasting instrument to facilitate innovation management.
Furthermore, a framework to understand decision-making in the adoption of strategic
tools is provided. This framework permits tools to be accepted on a more rational base
and curb the emotional and political influences which can act against the adoption of good
and effective tools
Laser surface engineering for enhanced functional performance
Get PDFThe work presented in this thesis covers a wide array of topics with a common theme,
i.e., laser texturing of surfaces for enhanced functionalization. These topics include: the
generation of superhydrophobic structures with nanosecond lasers, ablation and
texturing of stainless steel and tungsten carbide, friction reduction of surgical blade
instruments and friction reduction of machining inserts.
Superhydrophobic structures textured on stainless steel (SS304S15) with a
nanosecond pulsed laser are investigated. For the laser processing parameters
explored, as fluence increases so does the time required for the anti-wetting transition
to complete. In contrast to the reports found in the literature, the amount of carbon
detected at the surface did not change between the freshly textured samples and the
superhydrophobic samples.
In addition, this work provides framework in which ultra-short lasers (Amplitude
Satsuma 20W) can be used to generate grooves of varying dimensions i.e., a groove
width from 30 -180 µm and depth from 1 to 60 µm, in stainless steel (SS316) and
tungsten carbide (H101F) with a wide array of laser parameters.
The impact of surface texturing (grooves) on the friction between a contact composed
of SS316 and polyurethane—a common substitute for human flesh—is investigated
with the aid of a Tribometer, some textures were able to reduce the coefficient of
friction by up to ~20%. Furthermore, a reduction of up to ~14% in the scalpel blade
cutting force was measured using textured blades; the cutting tests displayed a partial
correlation to the friction tests.
The impact of surface texturing— with grooves and dimples of variable area ratio— on
the friction interactions between coated tungsten carbide inserts and a steel substrate
has been investigated. Whilst a reduction in the coefficient of friction of up to ~20%
was found for dimpled textures with area ratio of 10 and 20%, these could not be
correlated with the measured cutting forces. In addition, for most experimental
conditions no pattern could be recognised for the grooved structures. Typically having
a friction response similar to untextured surfaces —and in some cases higher
An empirical study into, and analysis of, the impact factors of effective digital content marketing in B2B marketing in the IT industry in Singapore
Get PDFThe introduction of the Internet and the growth in social media platforms provide
customers with vast information (Belch and Belch, 2017). However, customers no
longer want to receive and consume messages that are 'controlled' by marketers (Belch
and Belch, 2017). Customers want to participate by creating and contributing to the
messages (Kotler et al., 2010), which gave rise to Digital Content Marketing (DCM) as
a new way of communicating with customers (Solomon, 2013; Rao et al., 2014).
DCM that takes a publishing approach to provide targeted content (Holliman and
Rowley, 2014) and a storytelling approach to establish the brand's emotional connection
(Kee and Yazdanifard, 2015) could attract the audience more effectively than traditional
marketing (Pulizzi, 2015). Therefore, DCM was said to be the future of marketing
communications (Gábor, 2016).
DCM is more widely adopted by marketers in business-to-business (B2B) selling than
business-to-consumer (B2C) selling (Järvinen and Taiminen, 2016), and 70% of them
planned to produce more content for lead generation as the top objective (Pulizzi and
Handley, 2017a). Therefore, it is important to understand the impact factors of DCM
that could effectively generate sales leads, especially when B2B marketers are measured
on leads generation. Yet, academic research on DCM in B2B marketing is very
limited (Taiminen and Ranaweera, 2019).
This study identifies the impact factors of DCM for effective sales leads generation in
Singapore's B2B marketing in the Information Technology (IT) industry. From the
literature review, gap analysis and literature synthesis of existing research and literature
on this topic, four impact factors were identified, which formed the propositions for this
study. The four impact factors are emotionality in content, company-owned content,
referred content and job role.
The integrative methodology (Wright, 2011) aligned to the pragmatic research paradigm
(Johnson and Onwuegbuzie, 2004) was used in this study that combined both the
quantitative and qualitative methods, otherwise known as mixed methods (Firestone,
1987, Creswell, 2009). Digital content that displayed the impact factors being evaluated were created for the testing in a phenomenological research design. Using
the Sequential Explanatory Design approach to mixed methods, data were collected
using an online questionnaire from subjects to determine the extent to which the content
would interest them to find out more about the brand or product. After that, a semi structured interview was conducted to provide additional insights. The sample
comprises 203 Singapore-based IT decision-makers and influencers who leverage DCM
in the buying cycle of IT products for their organisations.
This study concludes that emotionality in content is more impactful in generating leads
among B2B customers than factual content. Marketing practitioners should leverage
storytelling to evoke emotions and interest in the products among customers, especially
at the early stage of their buying cycle when they have yet shortlisted brands or products
for consideration.
However, it is not conclusive whether company-owned content is more impactful than
referred content and vice versa. Customers would leverage company-owned content
when they have identified or shortlisted a few brands or products for comparison and
evaluation. On the other hand, referred content is regarded as useful when selecting
products for consideration and making the final decision.
This study also concludes that the impact of DCM and the impact factors varied by job
roles. Customers in non-IT related roles are more likely to turn to DCM for
information. Content that evokes emotions is impactful across all the job roles except
for IT leadership and developer roles. Company-owned content is preferred by
customers in IT-related roles, while referred content would impact customers across all
job roles, especially non-IT related roles. There is a significant difference in the
impact of DCM and the impact factors between IT managers and customers in non-IT
related roles.
The conclusions provide practical frameworks, recommendations and guidance to B2B
marketing practitioners on how to apply the impact factors to increase the Return on
Investment (ROI) of marketing spend on DCM. While this study is conducted in
Singapore due to the availability of subjects and its value to many IT companies
headquartered in Singapore, the findings may also be applied to the other Asia Pacific
and Western countries
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