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In this thesis, we develop a method to investigate the geometric quantisation of a hypertoric variety from an equivariant viewpoint, in analogy with the equivariant Verlinde formula for Higgs bundles. We do this by first using the residual circle action on a hypertoric variety to construct its symplectic cut that results in a compact cut space, which is needed for the localisation formulae to be well-defined and for the quantisation to be finite-dimensional. The hyperplane arrangement corresponding to the hypertoric variety is also affected by the symplectic cut, and to describe its effect we introduce the notion of a moment polyptych that is associated to the cut space. Also, we see that the prerequisite isotropy data that is needed for the localisation formulae can be read off from the combinatorial features of the moment polyptych. The equivariant Kawasaki-Riemann-Roch formula is then applied to the pre-quantum line bundle over each cut space, producing a formula for the equivariant character for the torus action on the quantisation of the cut space. Finally, using the quantisation of each cut space, we derive a formula expressing the dimension of each circle weight subspace of the quantisation of the hypertoric variety.

Quasicrystals are a class of materials that are long-range ordered yet not periodic. These unique features make them a fascinating middle ground between order and disorder, thus providing an ideal platform for studying a wealth of physical phenomena. This thesis contains three experimental works that my colleagues and I achieved during my PhD period, in which we explored the properties of quasicrystals in many aspects. The first experiment (Chapter 5) focus on the long-range order in quasicrystals. We report on the first experimental realisation of a two-dimensional (2D) quasicrystalline optical lattice for ultracold atoms and conduct matter-wave diffraction experiment using shot, intense lattice pulses. We reveal the different diffraction dynamics between periodic and quasiperiodic lattices and demonstrate the capability to simulate quantum walks on four-dimensional tight-binding lattices using the diffraction dynamics of 2D quasicrystalline lattices on short timescales. The second (Chapter 6) and the third (Chapter 7) experiments concentrate on studying the disorder nature of quasicrystals. In particular, we investigate disorder-induced localisation transition in the ground state of non-interacting and weakly interacting Bose gases in a 2D quasicrystalline lattice. The second experiment is mainly performed in the non-interacting limit, in which we probe the localisation transition by employing triangular lattice pulses and studying the time scale required for adiabatic loading. We observe a localisation transition at around a critical lattice depth of Vloc ≈ 1.78 Erec for noninteracting systems. In addition, we demonstrate that weak repulsive interactions can shift transition to deeper lattices. In the third experiment, we further study the interplay between the interactions and disorder, and constitute the first experimental realisation of the 2D Bose glass, an insulating but compressible groundstate phase without long-range phase coherence. By probing the coherent properties of the system, we observe a Bose glass to superfluid transition and map out the phase diagram in the weakly interacting regime. Moreover, we reveal the non-ergodic nature of the Bose glass by probing the capability of restoring coherence. Our observations are in good agreement with recent quantum Monte Carlo predictions and pave the way for experimentally testing of the connection between the Bose glass and many-body localisation.

Wheeled robots are subject to slip which may cause errors in position estimation if not correctly observed. Wheel slip is typically considered only by a path-following controller. An offline-calibrated slip value can also compensate for wheel odometry (WO). This thesis proposes a new method of fusing visual odometry (VO) and WO with integrated slip estimation using the Extended Kalman Filter. The approach handles the correlation between the slip and the rover's position estimation and occasional errors in any VO or WO measurements. Furthermore, it is possible to tune the model to emphasise WO (e.g. when no slip is expected and thus reduces the number of VO measurements) or rely more on VO (high slippage variability). An adaptive filter is introduced to tune both process and measurement noises automatically based on available measurements. It enables the assessment of noise statistics at each filter's iteration, leading to the design of a reactive VO scheduling algorithm. The solution does not rely on prior knowledge of the environment and offers a route to conserve computational resources while maintaining good navigational accuracy. The localisation system can be further improved if the wheel slip is known in advance. This prior information can be exploited by investigating how the wheel slip predictions, derived, for example, from forward-facing vision or motor current, can be fused within the model using different slip prediction schemes. The solutions provide improved localisation accuracy and hint at the intriguing possibility of slip-based SLAM. The above research scope was reduced to one dimension to lower the complexity and focus on the principles of new algorithms. However, to advance some elements described in this thesis, the adaptive filter with integrated slip estimation and reactive VO scheduling is expanded into two dimensions. The results demonstrate improved navigational performance but highlight the need for more work in the future.

This thesis examines the interplay of the local and global in lakhon phleng, also known as musical theatre, in Thailand through the lens of aesthetic cosmopolitanism. It constitutes the first systematic study on the contemporary scene of lakhon phleng, focusing on works from 1990 until 2021. In particular, this thesis argues that lakhon phleng is a product of an ongoing process of cultural hybridity, fusing elements from Thai aesthetics and decorum with those from external, largely Anglo-American, sources. As such, it has played an active role in the transnational flows of the musical theatre art form. In doing so, it analyses two key contemporary practitioners in Thai commercial musical theatre, Patravadi Mejudhon and Takonkiet Virawan. The former's musicals (active in the early 1990s) were mostly adapted from Thai classical literature and created in collaboration with international artists. The latter's big-budget musicals from 1997 onwards were so commercially successful that they sparked national interest in the art form of lakhon phleng and growth in the number of musical productions, theatre companies, and training programmes in urban Thailand. Apart from these two practitioners, this thesis examines an artistic project titled Musical Lab organised by practitioners of small-scale musical theatre, in which the researcher was directly involved. This project brought to light the perspectives of musical theatre practitioners, both professional and amateurs, in the small-scale musical theatre as well as key social factors that enabled subjects' mobility in the musical theatre community in Thailand. Despite the focus on recent history, this thesis also contextualises the present via a chronological discussion of lakhon phleng in Thailand from the reign of King Rama V (1868- 1910), examining the prototype of the art form known as lakhon rong and its early development by key practitioners such as Prince Narathip and Phran Bun who significantly shaped the art form's artistic styles and popularity. Written by a Thai musical theatre performer trained in Thailand, Singapore, and Britain, the thesis offers unique insights into lakhon phleng. Personal experiences of training and performing facilitate a discussion of performative techniques, enabling the analysis of hybridity in terms of both performance form and approach. Formal and informal interviews, hitherto untranslated research materials written in Thai, and first-hand experiences derived from witnessing performances and being involved with small-scale theatre in Thailand are incorporated into the analysis to offer unique insights into the ever-growing dialogues between local Thai and global musical theatre.

Ego-motion estimation in robotics is typically performed with cameras or laser sensors using established techniques that have proven successful in a variety of applications. While these advances have expanded the capabilities of au- tonomous systems, they are limited by sensor hardware that is adversely affected by poor weather and lighting conditions. Sensing with radar offers a robust means to perceive the environment in even the harshest conditions where these optical sensors fail. This thesis presents strategic improvements to a radar-only ego-motion estimation pipeline to extend its utility as a core component in an autonomous system. By leveraging information pertaining to the context in which the sensor is used, we offer a means to reduce processing time by filtering out spurious returns, predict failure using an introspective component, and estimate ego-motion with much greater accuracy by considering motion constraints. The first contribution uses a weakly-supervised approach to train a neural network that filters out radar returns not likely to correspond to static objects in the scene. By passing only those returns that are useful for ego-motion estimation, processing times are reduced by a factor of 2.36. Secondly, we propose a system that interprets the information encoded within the data association algorithm such that the overall confidence in a match between two radar landmark sets can be determined. A classifier is trained to distinguish between strong and weak correspondences and flag poor performance prior to taking action, reducing failure frequency by 24.7 %. Finally, we present a method which leverages information regarding the physical constraints of the robot platform to refine landmark correspondences. We discard those that suggest extreme ego-motion when under the assumption that the vehicle traverses paths of constant curvature. This includes a way to estimate relative pose from a single landmark observed twice, and reduces translational error in odometry by 45.94%. In each instance, validation is performed on real data captured from a vehicle- mounted scanning radar to measure the performance improvement of the proposed subsystem against a baseline Radar Odometry (RO) system. Through these data- driven advances, we seek to further the use of radar as a navigation sensor, so as to enable our robots to roam with greater efficiency, safety, and accuracy than before.

Localisation in wireless communication systems is an important topic that has many applications. Accurate geolocation in urban environments is a well understood challenge and Global Navigation Satellite System (GNSS) based technologies like GPS yield poor accuracy in non-line-of-sight (NLOS) scenarios. Use of multiple GNSS systems improves location accuracy but is still affected by urban canyons. Mobile network-based schemes offer an alternative, particularly when antenna arrays are deployed. Massive antenna arrays in Massive Multiple-Input-Multiple-Output (Massive MIMO) present an opportunity because of the possibility to use inexpensive, low-power and low-precision components with greatly reduced complexity/cost, in addition to Massive MIMO being a core component of 5G. This thesis reviews the problem of localisation in urban environments and investigates the techniques that are relevant towards achieving localisation in next generation wireless systems. It evaluates the NLOS problem and proposes schemes that use machine leaning techniques in the form of Least-Squares Support Vector Machines (LSSVMs), to address the challenges. It also investigates Direction of Arrival (DOA) estimation, which is a step towards localisation, using the Bristol Massive MIMO testbed. The proposed location specific approach presented in this thesis is a new framework which is shown to achieve a best case NLOS identification accuracy of greater than 98 percent. This result exceeds reported accuracies for existing NLOS identification techniques. Another proposed direct localisation approach achieves an 80th percentile probability location accuracy of 10 metres without utilising NLOS identification and mitigation. DOA estimation experiments demonstrate the possibility of performing estimation using subsets of antennas on a single base station antenna array. An outdoor experiment demonstrated a best case DOA RMSE of 2 degrees achieved for 3 different User Equipment (UE) positions. Overall, the results in this thesis demonstrate techniques that can be employed to solve the intermediate challenges towards device localisation and can contribute to the design and operation of next-generation systems. Significant benefits for mobile wireless systems can be derived from localisation. New handover strategies, new dynamic resource, power and pilot allocation schemes that take advantage of the location information, can also be developed.

Many countries and organisations around the world put forward important plans to source new knowledge that would help to accelerate their economic growth and competitive advantage. Within these plans, recruiting expatriate staff has been seen as an important means to acquire external knowledge. However, it has also been argued that overreliance on expatriate staffing may not be healthy for economic development, especially when local staff are left with very limited positions. In recognition of this issue governments, particularly those located in the Middle East, have established so-called "localisation", which refers to the replacement of expatriate staff by a local workforce. In this regard, since the 1970s the Gulf Cooperation Council (GCC) countries including Oman have set several plans to achieve localisation, but clearly these plans have not been entirely successful in terms of the targeted percentage of localisation. Scholars who have investigated this issue argue that the lack of skills and professionalism in the local workforce is one of the main obstacles for addressing this challenge. Therefore, based on the Ability, Motivation, and Opportunity Seeking (AMO) theory, this thesis contributes to the localisation and knowledge transfer literatures by developing a conceptual framework that aims to explore the extent to which transferring knowledge from expatriate managers to local staff in manufacturing companies, through certain mechanisms, helps to achieve successful localisation. Based on a positivist research philosophy and a quantitative approach, the current thesis has employed a self-administered, face-to-face questionnaire to collect data. The 327 completed questionnaires have been analysed to examin the hypotheses of the present study using Partial Least Squares Structural Equation Modelling (PLS-SEM) via Warp PLS V 6.0. The results have identified the essential factors for achieving successful localisation. First, the study has identified three essential competences for expatriate managers to transfer knowledge, namely: expatriate ability to transfer knowledge; expatriate motivation to transfer knowledge; and expatriate opportunity to transfer knowledge. Second, the study has shown that to achieve effective knowledge transfer and successful localisation, locals must have high absorptive capacity. Third, to enhance expatriate manager competences, the study has identified two essential sets of features to consider, the organisation characteristics and the knowledge characteristics. These findings thus provide several insights to the manufacturing companies seeking to achieve successful localisation. In terms of the practical implications, the current thesis has identified the key factors for achieving successful localisation. The first competence is that expatriate managers should have the ability to transfer knowledge. The second competence is related to expatriate manager motivation to transfer knowledge. The third competence is opportunity seeking to transfer knowledge. It has been proposed that in order to accomplish optimal performance of knowledge transfer, it is vital for expatriate to seek the opportunity to interact with the local staff. In this regard, opportunity seeking by expatriate managers would help knowledge seekers to get constant feedback as well as opportunities to clarify any ambiguity. In addition, it is critical for companies to acknowledge the absorptive capacity of local staff as an important factor for achieving successful localisation. In this vein, the findings of the current study have demonstrated that low absorptive capacity has adverse impacts on achieving successful localisation. Apart from the importance of knowledge-sender and knowledge-receiver competences, it is crucial to recognise the impact of organisational characteristics and knowledge characteristics on the competences of expatriate managers to transfer knowledge. With respect to the former, expatriate manager competences in transferring knowledge are influenced by organisational commitments to facilitate the process of knowledge acquisition and dissemination. As far knowledge characteristics, it has been concluded that in order to have effective knowledge transfer, companies are advised to provide important knowledge in explicit forms, such as blueprints and manuals, and to make them available and easily accessible to knowledge providers and seekers alike.

An increase in the demand of fossil resources has driven the construction and operation of oil and gas pipelines in remote and harsh environments, such as seismically-active, Arctic and deep-water regions. Pipelines installed and/or operated in these regions are subjected to large plastic straining, which poses a threat to the integrity of pipelines containing crack-like flaws. Pipeline steels often exhibit a yield discontinuity, known as the Lüders plateau, which further complicates analyses and assessments of pipelines containing flaws. This thesis aims to investigate the fracture behaviour of pipelines subjected to plastic straining, and to provide guidance for analysis and assessment of flawed pipes in the presence of yield discontinuity. This work contained both experiments and numerical analyses, including uniaxial tensile tests with and without notches, and single edged notch tension (SENT) tests, with the utilisation of Digital Image Correlation (DIC) techniques for strain measurement. The fracture behaviour of pipelines containing flaws with Lüders bands were further examined numerically. Finite element analysis (FEA) of pipelines containing circumferential flaws subjected to both uniaxial and biaxial loadings were conducted, respectively. Main contribution to the knowledge includes optimised material models identified by comparing numerical results against the published full-scale test results, and thereafter the influence of various flaw sizes and the pressure-induced stress biaxiality on the development of Lüders bands and the crack driving force of the flawed pipes. A clear understanding is achieved for the significant effects of the deforming and fracture behaviour of pipelines containing flaws subjected to both uniaxial and biaxial loading conditions, and in turn, of the flaw sizes and stress biaxility on the formation and development of Lüders behaviour. The findings provide enhanced design and operation guidance for pipelines with improved structural integrity.

The thesis presents the adaption of radio telemetry technology to allow for the tracking of the world’s most economically beneficial insect, the honeybee. Currently no technology is available to efficiently enable the long-term evaluation of navigation loss of bees exposed to potentially harmful pesticides such as neonicotinoids. The research aims at developing a self-sustained radio tracking device which can be attached to insects as small as the honeybee. The research presented within the thesis acts as a proof of principle for long range autonomous tracking of bees using a modified radio telemetry. To allow for compatibility of radio telemetry tags with smaller tags were designed and fabricated which implements a micro-generator that harvests electrical energy from the bee’s body vibrations which powers radio-wave transmission from a miniaturized antenna attached to the bees’ thorax. The use of lead zirconate titanate (PZT) allowed for sufficient power generation to replace the battery, whilst an increased operation frequency in comparison to current state of the art allowed for sufficient antenna size reduction. Both factors contributed to a significant weight reduction allowing for compatibility with honeybees. The successful transmission of the selfpowered radio telemetry tags is shown whilst outlining the effects of the battery replacement and increased frequency on the link budget of the system. A review of localisation systems for radio telemetry systems was performed in which alternative methods were investigated to allow for autonomous localisation of the radio telemetry tag with a single receiver. A compact phased array antenna affords angle of arrival (AOA) estimation and bee localisation through a received signal strength indicator approach (RSSI). The phased array antenna is capable of scanning +/-50° in azimuth and elevation. Additionally, a reflection type phase shifter capable of a 360° phase shift was designed and fabricated. Initial tests of the system were conducted in controlled environments and highlighted the system’s ability to detect and determine the AoA of a tagged bee within a 20m range. Further tests demonstrated the systems unobtrusive nature when monitoring the foraging times of tagged bees whilst recording their initial flight trajectories. Commercial applications of the system are shown in which the system is mounted within a polytunnel to monitor plant visitations and pollinator services on strawberry plants. To overcome the 20m detection range and achieve long range tracking of tagged bees the receiver unit was integrated to a drone in which the AOA estimate is autonomously fed into the control system of a drone, allowing for continuous position updates. The drone interprets the estimate in which a bearing is calculated before the drone autonomously moves towards the position of the AoA estimate. The experimental results show proof of concept towards autonomous tracking of tagged bees.

Indoor localisation of people and objects has been a focus of research studies for several decades because of its great advantage to several applications. Accuracy has always been a challenge because of the uncertainty of the employed sensors. Several technologies have been proposed and researched, however, accuracy still represents an issue. Today, several sensor technologies can be found in indoor environments, some of which are economical and powerful, such as Wi-Fi. Meanwhile, Smartphones are typically present indoors because of the people that carry them along, while moving about within rooms and buildings. Furthermore, vehicles such as mobility scooters can also be present indoor to support people with mobility impairments, which may be equipped with low-cost sensors, such as wheel encoders. This thesis investigates the localisation of mobility scooters operating indoor. This represents a specific topic as most of today's indoor localisation systems are for pedestrians. Furthermore, accurate indoor localisation of those scooters is challenging because of the type of motion and specific behaviour. The thesis focuses on improving localisation accuracy for mobility scooters and on the use of already available indoor sensors. It proposes a combined use of Wi-Fi, Smartphone IMU and wheel encoders, which represents a cost-effective energy-efficient solution. A method has been devised and a system has been developed, which has been experimented on different environment settings. The outcome of the experiments are presented and carefully analysed in the thesis. The outcome of several trials demonstrates the potential of the proposed solutions in reducing positional errors significantly when compared to the state-of-the-art in the same area. The proposed combination demonstrated an error range of 0.35m - 1.35m, which can be acceptable in several applications, such as some related to assisted living. 3 As the proposed system capitalizes on the use of ubiquitous technologies, it opens up to a potential quick take up from the market, therefore being of great benefit for the target audience.

Lifelong Learning is the development of human potential through a continuously supportive process which stimulates individuals to acquire knowledge and skills throughout their lifetimes (Dewey, 1910; Leicester & Field, 2000). It is significant both for the individual and the society in the 21st century, especially for China. Inspired by the Lisbon Key Competences (Cziboly, 2010) and Capability Approach, the author defined five core capabilities for lifelong learning related to this educational research: language capability, learning capability, creative capability, aesthetic and cultural capabilities, and social and civic capabilities. Drama in educational settings is the focus on the educational function to define drama as a teaching and learning method (DfES, 2003). It incorporates elements of an actor's training to facilitate students' physical, social, emotional and cognitive development. Drama used as a pedagogy in education is seen as a valuable tool for learning in many aspects related to language learning and lifelong learning (Cziboly, 2010). However, influenced by culture and history, drama pedagogy is less well developed in China compared to the West, in terms of both theory and practice. In this research, the author conducted a case study using drama pedagogy to design a drama program through "College Chinese" teaching in the Communication University of China. The two main research questions were 1) to explore the relationship between drama pedagogy and lifelong learning and 2) to discover the positive and negative effects of using drama pedagogy in the Chinese context. For the second question, the author used the concept of "localisation", which is the process of adapting a product or content to a specific locale or market. Although it is a term that is more often used in business and economics, the author used it in this research because it is closely related to the idea of adapting a teaching strategy from one distinct cultural area (e.g. the West) to another (e.g. China). This research contributes to the theory of the relationship between drama pedagogy and lifelong learning. It also has implications for the localisation of liberal pedagogy in indigenous contexts and the future educational reform in China.

The Asian summer monsoon circulation has been the subject of continuous research for several decades. Much emphasis has been given to the lower level cyclone, but while various models and mechanisms have been proposed to explain certain features of the upper level anticyclone, like the zonal scale or time dependence, a comprehensive theory combining these characteristics is still lacking. We re-visited the steady and linear 2D monsoon model proposed by Gill and Matsuno, which potentially captures the time-mean response of the flow, but fails to account for any kind of temporal evolution and requires a strong mechanical friction throughout the atmosphere, which is a questionable assumption for the upper troposphere/lower stratosphere region. We then re-modelled the monsoon flow as a response to a localised heat source using a numerical model that is able to capture the time dependence, non-linearity and three-dimensional nature of the system, which we see as necessary to successfully model the monsoon anticyclone. In addition to the explicit heating driving the monsoon we included a simple representation of mid-latitude dynamics into the model by imposing a relaxation towards a baroclinically unstable state. The simulated flow therefore includes mid-latitude westerly jets and baroclinic eddies. We then explored the parameter space by varying for example the forcing magnitude or the meridional temperature gradient of the basic state and investigated changes of the response. This way it was possible to identify various parameter combinations for which the response shows similar structures and behaviours to what has been observed in re-analysis data in relation to the monsoon anticyclone. This includes a finite zonal length scale of the response, as well as temporal evolution in the form of east- and westward shedding of eddies. Many characteristics of the behaviour of the upper level monsoon anticyclone can potentially be investigated by considering the dynamical evolution of a single fluid layer forced by a steady mass source. Such a single-layer model can be used to perform more in-depth studies than are possible in a 3D model. Using this approach we explained a variety of phenomena related to westward eddy shedding from the monsoon anticyclone as a consequence of an absolute instability of the flow field. By performing a comprehensive spatial stability analysis of an idealised representation of the system we were able to develop a theory for the transition between different shedding states. Adapting a simple analytic theory based on a centre-of-mass approach further allowed us to explain the near-steady propagation of the eddies shed from the monsoon. We also showed that the eddy propagation in our system is not modified by the fact that eddies are not well-separated and shed as a series of vortices, in contrast to findings of previous authors. By extending the theory and including a zonal background wind we were further able to explain some aspects of the changes due to thermal damping and the interaction of the flow with a zonal mean background wind like the mid-latitude jet. The presented study covers various observed features and behaviours of the Asian monsoon anticyclone and shows how they arise in simple dynamical models for certain ranges of values of external parameters.

This thesis, divided into two parts, is concerned with the analysis of spectral and dynamical characteristics of certain quantum spin systems in the presence of either I) quenched disorder, or II) dynamical noise. In the first part, the quantum random energy model (QREM), a mean-field spin glass model with a many-body localisation transition, is studied. In Chapter 2, we attempt a diagrammatic perturbative analysis of the QREM from the ergodic side, proceeding by analogy to the single-particle theory of weak localisation. Whilst we are able to describe diffusion, the analogy breaks down and a description of the onset of localisation in terms of quantum corrections quickly becomes intractable. Some progress is possible by deriving a quantum kinetic equation, namely the relaxation of the one-spin reduced density matrix is determined, but this affords little insight and extension to two-spin quantities is difficult. We change our approach in Chapter 3, studying instead a stroboscopic version of the model using the formalism of quantum graphs. Here, an analytic evaluation of the form factor in the diagonal approximation is possible, which we find to be consistent with the universal random matrix theory (RMT) result in the ergodic regime. In Chapter 4, we replace the QREM's transverse field with a random kinetic term and present a diagrammatic calculation of the average density of states, exact in the large-N limit, and interpret the result in terms of the addition of freely independent random variables. In the second part, we turn our attention to noisy quantum spins. Chapter 5 is concerned with noninteracting spins coupled to a common stochastic field; correlations arising from the common noise relax only due to the spins' differing precession frequencies. Our key result is a mapping of the equation of motion of n-spin correlators onto the (integrable) non-Hermitian Richardson-Gaudin model, enabling exact calculation of the relaxation rate of correlations. The second problem, addressed in Chapter 6, is that of the dynamics of operator moments in a noisy Heisenberg model; qualitatively different behaviour is found depending on whether or not the noise conserves a component of spin. In the case of nonconserving noise, we report that the evolution of the second moment maps onto the Fredrickson-Andersen model - a kinetically constrained model originally introduced to describe the glass transition. This facilitates a rigorous study of operator spreading in a continuous-time model, providing a complementary viewpoint to recent investigations of random unitary circuits.

This Doctor of Business Administration (DBA) thesis is about identifying the key factors which affect knowledge transfer between individuals in private sector companies in Saudi Arabia and Qatar. A DBA differs from a Doctor of Philosophy (PhD) in its application to live issues rather than the mainly theoretical academic approach in the PhD; is normally business based; and has the potential to make improvement to practice. It is widely recognised that knowledge transfer is fundamental to organisational success and in providing a source of strategic competitive advantage. Middle East countries offer Western businesses growth potential but it is often associated with Localisation of jobs. Successful knowledge transfer could be an important differentiator in achieving Localisation. The aim of this exploratory study was to investigate knowledge transfer between Western Expatriates and Nationals to provide an understanding of the strategic context; to identify the individual key factors involved; to create practitioner guidelines; and to contribute to the academic literature. A qualitative field study, adopting multiple case research design, was used to investigate one company in Saudi Arabia and 2 companies in Qatar. Semi-structured interviews with 31 individuals, based on an existing conceptual framework, were the primary source of data. Direct observation and documentary evidence were secondary sources of data. This study appears to be the first to investigate and compare Expatriate and National knowledge transfer experience in two GCC countries. The main findings were that individual knowledge transfer was being undertaken in the strategic context of Saudisation and Qatarisation. Like other studies, organisational culture and leadership positively and negatively affected knowledge transfer. The positive motivators for Nationals appear to be money, recognition, ambition and self-fulfilment. Their negative motivators seem to be a sense of entitlement and under-confidence. For Expatriates, positive motivators were largely absent whilst a fear of conflict and job insecurity were key negative factors. Expatriate job insecurity led to a Deter-Defer-Delay strategy for knowledge hiding which extends the literature of this emerging concept. Mutual cultural stereotyping also appears to inhibit individual knowledge transfer. The overall practitioner conclusion is that companies should consider how to demonstrate commitment to Localisation through locally adapted policies and leaders should provider commitment and time for knowledge transfer. Nationals need to be selected with values aligned to the company and expectations managed. Expatriates need to be selected and trained to be more culturally aware; have more job security and more organisational support. Future research into Expatriate Deter-Defer-Delay strategies and the testing of the revised conceptual framework, on a longitudinal basis, in other GCC countries, is recommended.

The introduction of creases into thin sheets has a dramatic effect on their global mechanical properties. This can be observed by manipulating a crumpled piece of paper which has been unfolded; it no longer deforms in the same way as the original sheet. Creases have typically been modelled as singular hinge lines, often accompanied by a torsional spring to provide some opening resistance; however, the appropriate stiffness of these springs is unclear. In reality, creases have a discrete geometry based on the method they were formed. This dissertation investigates the flexural behaviour of a creased thin metallic strip and the influence of the crease geometry. When a strip is bent perpendicular to the crease, putting the crease region in tension and the strip edges in compression, initially torsional deformations occur which ultimately coalesce into a central localised flattened region. An analytical model of this flexural behaviour is developed, which idealises the crease as an initially circular segment. Predictions show the bending resistance increases as the crease decreases in size. The model predictions are compared to finite element analysis and experimental results showing excellent agreement. When a strip is bent in the opposite direction, with the crease region in compression and the strip edges in tension, a bistable snap-through occurs. The deformed shape is characterised by a sharp vertex on the crease line. An analytical model is developed by generalising a Gauss mapping approach, and used to predict the deformed shape. These predictions match experimental results well. This dissertation provides an understanding of the mechanics of creased thin strips, where the crease is given a discrete geometry, and explores the nature of localisation. It also provides the foundation to explore the mechanics of thin sheets featuring a network of creases. This offers the opportunity to improve the efficiency of thin shell structures by using creasing to optimise the mechanics, leading to reduced material use, more sustainable construction, and fuel savings from lighter vehicles.

This thesis is an attempt to make visible how Christians within a minority people in the southern Philippines view the Bible conceptually as a source of spiritual authority and also how they read and interpret the Bible, both privately and within the context of community worship. Reading and studying the Bible is now universally practised by people from multitudes of cultures, a reality that has naturally engendered a great deal of interest on the part of scholars. The resultant scholarship however, has been preoccupied with the findings of the professional researcher, and little has been published which reveals how “ordinary indigenous readers” view the Bible and/or how they interpret it. Using qualitative data gathered by this author among Manobo Christians living in the hills of central Mindanao, this thesis will endeavour to redress this imbalance and provide access to the voices of ordinary Manobo readers. The thesis also makes an important contribution to the Bible’s place within Philippine Christianity. Despite the expanding readership of the Bible within the Philippines almost no research has focused on how the Bible is actually interpreted by ordinary readers. The thesis will major on the appropriation of the Bible by Christians from within the Manobo Bible Church Association of Mindanao, an association of churches born out of the church planting efforts of missionaries belonging to the Overseas Missionary Fellowship. At the centre of the thesis is an encounter between conservative evangelical missionaries and the unique culture and cosmology of the Manobo. The central argument is that the missionaries’ prototypically, evangelical doctrine of Scripture was appropriated and reconfigured by Manobo Christians in ways that reveal the persistent ability of elements of their own cosmology, and customary law, to exert influence upon their localisation of Christianity. In particular, the thesis focuses on how the localisation process has led to innovations by the Manobo on what is meant by the Bible as “spiritual authority” and to reinterpretations of significant theological themes within the evangelical gospel message. At the same time the thesis also outlines how adoption of the Christian Scriptures has redefined the position that indigenous sources of authority, such as spirit priest and village chief, now occupy within Manobo Christian communities.

Animals are often able to solve complex navigational tasks in very challenging terrain, despite using low resolution sensors and minimal computational power, providing inspiration for robots. In particular, many species of insect are known to solve complex navigation problems, often combining an array of different behaviours (Wehner et al., 1996; Collett, 1996). Their nervous system is also comparatively simple, relative to that of mammals and other vertebrates. In the first part of this thesis, the visual input of a navigating desert ant, Cataglyphis velox, was mimicked by capturing images in ultraviolet (UV) at similar wavelengths to the ant’s compound eye. The natural segmentation of ground and sky lead to the hypothesis that skyline contours could be used by ants as features for navigation. As proof of concept, sky-segmented binary images were used as input for an established localisation algorithm SeqSLAM (Milford and Wyeth, 2012), validating the plausibility of this claim (Stone et al., 2014). A follow-up investigation sought to determine whether using the sky as a feature would help overcome image matching problems that the ant often faced, such as variance in tilt and yaw rotation. A robotic localisation study showed that using spherical harmonics (SH), a representation in the frequency domain, combined with extracted sky can greatly help robots localise on uneven terrain. Results showed improved performance to state of the art point feature localisation methods on fast bumpy tracks (Stone et al., 2016a). In the second part, an approach to understand how insects perform a navigational task called path integration was attempted by modelling part of the brain of the sweat bee Megalopta genalis. A recent discovery that two populations of cells act as a celestial compass and visual odometer, respectively, led to the hypothesis that circuitry at their point of convergence in the central complex (CX) could give rise to path integration. A firing rate-based model was developed with connectivity derived from the overlap of observed neural arborisations of individual cells and successfully used to build up a home vector and steer an agent back to the nest (Stone et al., 2016b). This approach has the appeal that neural circuitry is highly conserved across insects, so findings here could have wide implications for insect navigation in general. The developed model is the first functioning path integrator that is based on individual cellular connections.

We investigate various relationships between categories of functors. The major examples are given by extending some duality to a larger structure, such as an adjunction or a recollement of abelian categories. We prove a theorem which provides a method of constructing recollements which uses 0-th derived functors. We will show that the hypotheses of this theorem are very commonly satisfied by giving many examples. In our most important example we show that the well-known Auslander-Gruson-Jensen equivalence extends to a recollement. We show that two recollements, both arising from different characterisations of purity, are strongly related to each other via a commutative diagram. This provides a structural explanation for the equivalence between two functorial characterisations of purity for modules. We show that the Auslander-Reiten formulas are a consequence of this commutative diagram. We define and characterise the contravariant functors which arise from a pp-pair. When working over an artin algebra, this provides a contravariant analogue of the well-known relationship between pp-pairs and covariant functors. We show that some of these results can be generalised to studying contravariant functors on locally finitely presented categories whose category of finitely presented objects is a dualising variety.

The ability to precisely determine one's location in within the world (localisation) is a key requirement for any robot wishing to navigate through the world. For long-term operation, such a localisation system must be robust to changes in the environment, both short term (eg. traffic, weather) and long term (eg. seasons). This thesis presents two methods for performing such localisation using cameras - small, cheap, lightweight sensors that are universally available. Whilst many image-based localisation systems have been proposed in the past, they generally rely on either feature matching, which fails under many degradations such as motion blur, or on photometric consistency, which fails under changing illumination. The methods we propose here directly align images with a dense prior map. The first method uses maps synthesised from a combination of LIDAR scanners to generate geometry and cameras to generate appearance, whilst the second uses vision for both mapping and localisation. Both make use of an information-theoretic metric, Normalised Information Distance (NID), for image alignment, relaxing the appearance constancy assumption inherent in photometric methods. Our methods require significant computational resources, but through the use of commodity GPUs, we are able to run them at a rate of 8-10Hz. Our GPU implementations make use of low level OpenGL, enabling compatibility across almost any GPU hardware. We also present a method for calibrating multi-sensor systems, enabling the joint use of cameras and LIDAR for mapping. Through experiments on both synthetic data and real-world data from over 100km of driving outdoors, we demonstrate the robustness of our localisation system to large variations in appearance. Comparisons with state-of-the-art feature-based and direct methods show that ours is significantly more robust, whilst maintaining similar precision.

The physics of two-phase systems is explored here, particularly magneto-transport and low temperature d.c. conductivity in thin films. The extraordinary magnetoresistance (EMR) effect was analysed in the context of previous experimental and theoretical considerations. The magnetoresistance (MR) may be enhanced by up to two orders of magnitude by changing the geometry. This was investigated using finite element analysis. Thin film samples consisting of a layered structure of Germanium-Tin-Germanium (Ge-Sn-Ge) were created in collaboration with Shandong University in China. Ge layers were kept at a constant thickness across all samples, with variable Sn thickness. Regions of Sn form island-like shapes ten times larger than the average film thickness, as is seen in scanning electron microscope (SEM) images. Raman spectroscopy was conducted on these samples, from which it is concluded that the Ge layers are amorphous in nature. It was seen that there is a relationship between the electrical resistance and the film thickness which is indicative of a metal-insulator transition (MIT). The temperature dependence of resistivity was subsequently investigated. The temperature coefficient of resistivity (TCR) of the samples is seen to become negative as the thickness of the Sn layer is reduced below a certain critical thickness. Depending on their thickness, samples were designated as metallic or insulator, and various models associated with metals and insulators fitted to the data. While it is impossible to be absolutely certain of the validity of each of the models, some are a better fit than others. The same temperature dependence of resistivity was measured with an applied magnetic field. This is compared with the previous EMR investigation, however the MR of the samples is only of the order of a few percent which corresponds to ordinary MR, seen in most metals. The magnetic field measurements suppress a resistivity down-turn at very low temperatures (T < 10K) which suggests the presence of superconductivity. Analysis of dr=dT shows that the onset of superconductivity is lower for samples with a lower Sn thickness. Additionally, the deposition rate of the Sn layer affects the resistivity significantly; a higher deposition rate causes a decrease in resistivity. It is supposed that this is due to a change in the microstructure of the film. Finally, piezo-resistivity was considered by applying mechanical compression to the samples. The added pressure causes a drop in resistivity.

Electrical Impedance Tomography (EIT) is a medical imaging technique in which images of tissue conductivity within a body can be inferred from surface electrode measurements. The main goal of this study is to develop a portable EIT system incorporating an optimized electrode layout to detect intracranial haematomas for use in emergency care. A growing haematoma can cause severe and even permanent damage to the delicate tissue of the brain, morbidity, and eventual death of the patient. No capability is at present available for the diagnosis of haematomas pre-hospitalisation or by first-responders. The lack of this crucial information can lead to bad decisions on patient management, and in particular, where to send the patient. Blood has a high electrical conductivity contrast relative to other cranial tissue and can be detected and monitored using electrical impedance methods. EIT is a non-invasive, low-cost monitoring alternative to other imaging modalities, and has the potential to detect bleeding and to localize the approximate bleeding site. A device of this nature would reduce treatment delays, save on costs and waste, and most significantly, positively impact patient outcomes. The first step was a numerical simulation study on FE models. The full array and the hemi-array electrode layouts were modelled and the anomalies were simulated in different positions with different sizes. The results were obtained using TSVD and WMNM reconstruction methods by COMSOL linked with MATLAB. The simulated anomalies were detected for all the positions using both layouts; however those from the full array were in general superior to the hemi-array. In order to perform realistic experiments, a prototype EIT system was constructed in the laboratory. The constructed EIT has 16 channels and operates in the frequency range of 10 kHz to 100 kHz with a temporal resolution of 100 frames per second and high level of accuracy of 93.5 %. The minimum number of 8 electrodes was chosen in this study for emergency care. Minimizing the number of electrodes speeds up the electrode setup process and avoids the need to move the patient s head in emergency care. In the second part of this study, phantom experiments were performed to find an optimised electrode layout for emergency care. The full array and the hemi-array were investigated using phantom experiments. As expected, the full array layout had the best performance in general; however, the performance of the hemi-array layout was very poor. Thus a novel optimised electrode layout (semi-array) for emergency care was proposed and evaluated in phantom experiments. For the hemi-array and the semi-array layouts, measurement sensitivity depends strongly on the anomaly location since the electrodes are not placed all over the head. The HA layout performed very badly, with the best radial localization error of 0.8100 mm, compared to the SA layout with the worst error of 0.2486 mm. Some reconstructed anomalies located far from the electrodes in the posterior region were almost invisible or erroneous for the hemi-array layout; however, it is enhanced by using the semi-array layout. Finally, in vitro experiments were conducted on ovine models. In most of the experiments carried out by other researchers, since the location of the simulated anomalies was not known and the simulated blood was normally injected into the body or the head, localization of the anomalies was not considered and the quantity of the injected blood was investigated solely. In our new method of experiment, the position of the anomalies was known a priori and thus could be compared accurately to the EIT results. The full array and the semi-array layouts were compared in terms of detection, localisation and size estimation of haematomas. As expected, the full array layout was found to be more robust than the semi-array layout with the best mean value of the localization error of 0.0564 mm and the worst QI error of around 30%. Using a minimum number of electrodes in an optimised layout is always desirable in clinical applications. The semi-array 8-electrode layout prevents unnecessary movements and the electrode connections to the head would be very quick in emergency care. Although the semi-array 8-electrode layout reduced the sensitivity of the measurements, the findings from the experiments indicated its potential to detect and monitor haematomas and probably extend its application for emergency applications where the required accuracy is not critical.

This thesis considers the domain of acoustic source localisation and tracking in an indoor environment. Acoustic tracking has applications in security, human-computer interaction, and the diarisation of meetings. Source localisation and tracking is typically a computationally expensive task, making it hard to process on-line, especially as the number of speakers to track increases. Much of the literature considers single-source localisation, however a practical system must be able to cope with multiple speakers, possibly active simultaneously, without knowing beforehand how many speakers are present. Techniques are explored for reducing the computational requirements of an acoustic localisation system. Techniques to localise and track multiple active sources are also explored, and developed to be more computationally efficient than the current state of the art algorithms, whilst being able to track more speakers. The first contribution is the modification of a recent single-speaker source localisation technique, which improves the localisation speed. This is achieved by formalising the implicit assumption by the modified algorithm that speaker height is uniformly distributed on the vertical axis. Estimating height information effectively reduces the search space where speakers have previously been detected, but who may have moved over the horizontal-plane, and are unlikely to have significantly changed height. This is developed to allow multiple non-simultaneously active sources to be located. This is applicable when the system is given information from a secondary source such as a set of cameras allowing the efficient identification of active speakers rather than just the locations of people in the environment. The next contribution of the thesis is the application of a particle swarm technique to significantly further decrease the computational cost of localising a single source in an indoor environment, compared the state of the art. Several variants of the particle swarm technique are explored, including novel variants designed specifically for localising acoustic sources. Each method is characterised in terms of its computational complexity as well as the average localisation error. The techniques’ responses to acoustic noise are also considered, and they are found to be robust. A further contribution is made by using multi-optima swarm techniques to localise multiple simultaneously active sources. This makes use of techniques which extend the single-source particle swarm techniques to finding multiple optima of the acoustic objective function. Several techniques are investigated and their performance in terms of localisation accuracy and computational complexity is characterised. Consideration is also given to how these metrics change when an increasing number of active speakers are to be localised. Finally, the application of the multi-optima localisation methods as an input to a multi-target tracking system is presented. Tracking multiple speakers is a more complex task than tracking single acoustic source, as observations of audio activity must be associated in some way with distinct speakers. The tracker used is known to be a relatively efficient technique, and the nature of the multi-optima output format is modified to allow the application of this technique to the task of speaker tracking.

Robust localisation is a key requirement for autonomous vehicles. However, in order to achieve widespread adoption of this technology, we also require this function to be performed using low-cost hardware. Cameras are appealing due to their information-rich image content and low cost; however, camera-based localisation is difficult because of the problem of appearance change. For example, in outdoor en- vironments the appearance of the world can change dramatically and unpredictably with variations in lighting, weather, season and scene structure. We require autonomous vehicles to be robust under these challenging environmental conditions. This thesis presents Dub4, a vision-only localisation system for autonomous vehicles. The system is founded on the concept of experiences, where an "experience" is a visual memory which models the world under particular conditions. By allowing the system to build up and curate a map of these experiences, we are able to handle cyclic appearance change (lighting, weather and season) as well as adapt to slow structural change. We present a probabilistic framework for predicting which experiences are most likely to match successfully with the live image at run-time, conditioned on the robot's prior use of the map. In addition, we describe an unsupervised algorithm for detecting and modelling higher-level visual features in the environment for localisation. These features are trained on a per-experience basis and are robust to extreme changes in appearance, for example between rain and sun, or day and night. The system is tested on over 1500km of data, from urban and off-road environments, through sun, rain, snow, harsh lighting, at different times of the day and night, and through all seasons. In addition to this extensive offline testing, Dub4 has served as the primary localisation source on a number of autonomous vehicles, including the Oxford University's RobotCar, the 2016 Shell Eco-Marathon, the LUTZ PathFinder Project in Milton Keynes, and the GATEway Project in Greenwich, London.

Oil and Gas companies have the inevitable need to operate in a global environment and therefore have a global reach. This thesis seeks to understand the nature and degree of localisation of the websites in this industry. This thesis introduces two notions of ‘global’, and seeks to examine the relationship between them: the first of which is the Global reach or operations of companies and the second is where a company’s communication is localised in language and cultural terms. A company can be seen to be ‘global’ in one of these two notions and it is this relationship that this thesis seeks to explore. The contribution of this thesis firstly, is that it adds to previous studies of website localisation, which have focused primarily on consumer goods and the retail industry, by examining a different kind of industry. Secondly, it takes into account the important semiotic and symbolic dimensions of language and culture when looking at localisation practices. The thesis thus contributes to the growing literature on website localisation and practices in Multinational companies. This study was carried out on 387 corporate and country specific websites of 16 Oil and Gas Companies to understand the extent and nature of their localisation practises particularly the way that language and culture are presented. The websites were studied using a qualitative and quantitative research design which involved carrying out a linguistic/semiotic analysis and a cultural analysis to give a balanced perspective of localisation practices. The conclusions of the study were that the companies operated a ‘glocal’ strategy, a combination of both a localised and a globalised (standardised) strategy. The companies had a combination of globally standardised features such as the website layouts, images, colour schemes, logos and the use of global celebrities on their websites and a limited degree of localisation where the ‘local’ is signified by local country websites, local news stories, local languages, local celebrities, images of local sights, images of company’s local office buildings and local petrol stations.

This study is devoted to investigating and developing WSN based localisation approaches with high position accuracies indoors. The study initially summarises the design and implementation of localisation systems and WSN architecture together with the characteristics of LQI and RSSI values. A fingerprint localisation approach is utilised for indoor positioning applications. A k-nearest neighbourhood algorithm (k-NN) is deployed, using Euclidean distances between the fingerprint database and the object fingerprints, to estimate unknown object positions. Weighted LQI and RSSI values are calculated and the k-NN algorithm with different weights is utilised to improve the position detection accuracy. Different weight functions are investigated with the fingerprint localisation technique. A novel weight function which produced the maximum position accuracy is determined and employed in calculations. The study covered designing and developing the centroid localisation (CL) and weighted centroid localisation (WCL) approaches by using LQI values. A reference node localisation approach is proposed. A star topology of reference nodes are to be utilized and a 3-NN algorithm is employed to determine the nearest reference nodes to the object location. The closest reference nodes are employed to each nearest reference nodes and the object locations are calculated by using the differences between the closest and nearest reference nodes. A neighbourhood weighted localisation approach is proposed between the nearest reference nodes in star topology. Weights between nearest reference nodes are calculated by using Euclidean and physical distances. The physical distances between the object and the nearest reference nodes are calculated and the trigonometric techniques are employed to derive the object coordinates. An environmentally adaptive centroid localisation approach is proposed. Weighted standard deviation (STD) techniques are employed adaptively to estimate the unknown object positions. WSNs with minimum RSSI mean values are considered as reference nodes across the sensing area. The object localisation is carried out in two phases with respect to these reference nodes. Calculated object coordinates are later translated into the universal coordinate system to determine the actual object coordinates. Virtual fingerprint localisation technique is introduced to determine the object locations by using virtual fingerprint database. A physical fingerprint database is organised in the form of virtual database by using LQI distribution functions. Virtual database elements are generated among the physical database elements with linear and exponential distribution functions between the fingerprint points. Localisation procedures are repeated with virtual database and localisation accuracies are improved compared to the basic fingerprint approach. In order to reduce the computation time and effort, segmentation of the sensing area is introduced. Static and dynamic segmentation techniques are deployed. Segments are defined by RSS ranges and the unknown object is localised in one of these segments. Fingerprint techniques are applied only in the relevant segment to find the object location. Finally, graphical user interfaces (GUI) are utilised with application program interfaces (API), in all calculations to visualise unknown object locations indoors.

This thesis presents novel solutions for two fundamental problems associated with autonomous road driving. The first is accurate and persistent localisation and the second is automatic extrinsic sensor calibration. We start by describing a stereo Visual Odometry (VO) system, which forms the basis of later chapters. This sparse approach to ego-motion estimation leverages the efficacy and speed of the BRIEF descriptor to measure frame-to-frame correspondences and infer subsequent motion. The system is able to output locally metric trajectory estimates as demonstrated on many kilometres of data. We then present a robust vision only localisation system based on a two-stage approach. Firstly we gather a representative survey in ideal weather and lighting conditions. We then leverage locally accurate VO trajectories to synthesise a high resolution orthographic image strip of the road surface. This road image provides a highly descriptive and stable template against which to match subsequent traversals. During the second phase, localisation, we use the VO to provide high frequency pose updates, but correct for the drift inherent in all locally derived pose estimates with low frequency updates from a dense image matching technique. Here a live image stream is registered against synthesised views of the road image generated form the survey. We use an information theoretic measure, Mutual Information, to determine the alignment of live images and synthesised views. Using this measure we are able to successfully localise subsequent traversals of surveyed routes under even the most intense lighting changes expected in outdoor applications. We demonstrate our system localising in multiple environments with accuracy commensurate to that of an Inertial Navigation System. Finally we present a technique for automatically determining the extrinsic calibration between a camera and Light Detection And Ranging (LIDAR) sensor in natural scenes. Rather than requiring a stationary platform as with prior art, we actually exploit platform motion allowing us to aggregate data and adopt a retrospective approach to calibration. Coupled with accurate timing this retrospective approach allows for sensors with non-overlapping fields of view to be calibrated as long as at some point the observed workspaces overlap. We then show how we can improve the accuracy of our calibration estimates by treating each single shot estimate as a noisy measurement and fusing them together using a recursive Bayes filter. We evaluate the calibration algorithm in multiple environments and demonstrate millimetre precision in translation and deci-degrees in rotation.

Accurate and robust localisation is a fundamental aspect of any autonomous mobile robot. However, if these are to become widespread, it must also be available at low-cost. In this thesis, we develop a new approach to localisation using monocular cameras by leveraging a coloured 3D pointcloud prior of the environment, captured previously by a survey vehicle. We make no assumptions about the external conditions during the robot's traversal relative to those experienced by the survey vehicle, nor do we make any assumptions about their relative sensor configurations. Our method uses no extracted image features. Instead, it explicitly optimises for the pose which harmonises the information, in a Shannon sense, about the appearance of the scene from the captured images conditioned on the pose, with that of the prior. We use as our objective the Normalised Information Distance (NID), a true metric for information, and demonstrate as a consequence the robustness of our localisation formulation to illumination changes, occlusions and colourspace transformations. We present how, by construction of the joint distribution of the appearance of the scene from the prior and the live imagery, the gradients of the NID can be computed and how these can be used to efficiently solve our formulation using Quasi-Newton methods. In order to reliably identify any localisation failures, we present a new classifier using the local shape of the NID about the candidate pose and demonstrate the performance gains of the complete system from its use. Finally, we detail the development of a real-time capable implementation of our approach using commodity GPUs and demonstrate that it outperforms a high-grade, commercial GPS-aided INS on 57km of driving in central Oxford, over a range of different conditions, times of day and year.

In order for autonomous vehicles to achieve life-long operation in outdoor environments, navigation systems must be able to cope with visual change---whether it's short term, such as variable lighting or weather conditions, or long term, such as different seasons. As a GPS is not always reliable, autonomous vehicles must be self sufficient with onboard sensors. This thesis examines the problem of localisation against a known map across extreme lighting and weather conditions using only a stereo camera as the primary sensor. The method presented departs from traditional techniques that blindly apply out-of-the-box interest-point detectors to all images of all places. This naive approach fails to take into account any prior knowledge that exists about the environment in which the robot is operating. Furthermore, the point-feature approach often fails when there are dramatic appearance changes, as associating low-level features such as corners or edges is extremely difficult and sometimes not possible. By leveraging knowledge of prior appearance, this thesis presents an unsupervised method for learning a set of distinctive and stable (i.e., stable under appearance changes) feature detectors that are unique to a specific place in the environment. In other words, we learn place-dependent feature detectors that enable vastly superior performance in terms of robustness in exchange for a reduced, but tolerable metric precision. By folding in a method for masking distracting objects in dynamic environments and examining a simple model for external illuminates, such as the sun, this thesis presents a robust localisation system that is able to achieve metric estimates from night-today or summer-to-winter conditions. Results are presented from various locations in the UK, including the Begbroke Science Park, Woodstock, Oxford, and central London.

Progress in micro-electromechanical systems (MEMS) and radio frequency (RF) technology has fostered the development of wireless sensor networks (WSNs). Different from traditional networks, WSNs are data-centric, self-configuring and self-healing. Although WSNs have been successfully applied in built environments (e.g. security and services in smart homes), their applications and benefits have not been fully explored in areas such as disaster recovery and rescuing. There are issues related to self-localisation as well as practical constraints to be taken into account. The current state-of-the art communication technologies used in disaster scenarios are challenged by various limitations (e.g. the uncertainty of RSS). Localisation in WSNs (location sensing) is a challenging problem, especially in disaster environments and there is a need for technological developments in order to cater to disaster conditions. This research seeks to design and develop novel localisation algorithms using WSNs to overcome the limitations in existing techniques. A novel probabilistic fuzzy logic based range-free localisation algorithm (PFRL) is devised to solve localisation problems for WSNs. Simulation results show that the proposed algorithm performs better than other range free localisation algorithms (namely DVhop localisation, Centroid localisation and Amorphous localisation) in terms of localisation accuracy by 15-30% with various numbers of anchors and degrees of radio propagation irregularity. In disaster scenarios, for example, if WSNs are applied to sense fire hazards in building, wireless sensor nodes will be equipped on different floors. To this end, PFRL has been extended to solve sensor localisation problems in 3D space. Computational results show that the 3D localisation algorithm provides better localisation accuracy when varying the system parameters with different communication/deployment models. PFRL is further developed by applying dynamic distance measurement updates among the moving sensors in a disaster environment. Simulation results indicate that the new method scales very well.

Work described in this thesis is concerned with localisation techniques, for determining the position, of wireless sensors whilst these are immersed in confined industrial processes, such as those occurring in the chemical, pharmaceutical and food processing industries. Two different approaches to localisation were investigated. The first approach employed an existing hardware system that used ultra wide band (UWB) signals whist the second approach used a network localisation method based on information from narrow-band received signals. A prototype UWB-based localisation algorithm processed experimental received UWB pulses to detect their leading edges (LE) that were used to derive Time Difference of Arrival (TDoA) data. In turn TDoA data were converted into distances and used to compute the locations of the sensor nodes. Nevertheless, the process of detecting the LEs caused significant errors in the localisation process. To deal with this problem new automated adaptive LE detection methods were derived that succeeded in reducing localisation errors by half, compared to the prototype method, reaching accuracies of ±2cm. Thorough analysis of TDoA profiles revealed that these follow specific trends depending on the positions of the sensor nodes. A number of properties of TDoA profiles are proved mathematically and incorporated into seven localisation algorithms. These algorithms were examined using experimental TDoA data and shown to achieve average localisation errors up to 3cm. Network-based localisation was examined at a later stage of this research since complexities of large scale measurements and difficulties with equipment, delayed acquiring experimental data. The deployed network consisted of a number of nodes whose positions were known (anchors) that were used to estimate the positions of sensor nodes whose positions where considered to be unknown. Localisation was based on received signal strength (RSS) data, at every node to be localised, in anticipation that RSS could provide distance information that could be used in the localisation procedure. Nevertheless, fluctuations in RSS only allowed using localisation algorithms that associated RSS to the positions of anchors. The average localisation error in the network-based localisation algorithms was between 30cm to 100cm.

Truly autonomous operation for any field robot relies on a well-defined pyramid of technical competencies. Consider the case of an autonomous car – we require the vehicle to be able to perceive its environment through noisy sensors, robustly fuse this information into an accurate representation of the world, and use this representation to plan and execute complex tasks – all the while dealing with the uncertainties inherent in real world operation. Of fundamental importance to all these capabilities is localisation – we always need to know where we are, if we are to be able to plan where we are going (or how to get there). As road vehicles make the push towards becoming truly autonomous, the system’s ability to stay accurately localised over its operating lifetime is of crucial importance – this is the core issue of lifelong localisation. The goals in this thesis are threefold – to develop the hardware needed to reliably acquire data over large scales, to build a localisation framework that is robust enough to be used over the long–term, and to establish a method of adapting our framework when necessary such that we can accommodate the inevitable difficulties present when operating over city-scales. We begin by developing the physical means to make large-scale localisation achievable, and affordable. This takes the form of a stand-alone, rugged sensor payload – incorporating a number of sensing modalities – that can be deployed in either a mapping or localisation role. We then present a new technique for localisation in a prior map using an information theoretic framework. The core idea is to build a dense retrospective sensor history, which is then matched statistically within a prior map. The underlying idea is to leverage the persistent structure in the environment, and we show that by doing so, it is possible to stay localised over the course of many months and kilometres. The developed system relies on orthogonally-oriented ranging sensors, to infer both velocity and pose. However, operating in a complex, dynamic, setting (like a town centre) can often induce velocity errors, distorting our sensor history and resulting in localisation failure. The insight into dealing with this failure is to learn from sensor context – we learn a place-dependent sensor model and show that doing so is vital to prevent such failures. The integration of these three competencies gives us the means to make inex- pensive, lifelong localisation an achievable goal.

This thesis concerns the development of optimisation algorithms to determine the relative co-location, (localisation), of a number of freely-flying 'Smart Dust mote' sensor platform elements using a non-deterministic data-set derived from the duplex wireless transmissions between elements. Smart dust motes are miniaturised, microprocessor based, electronic sensor platforms, frequently used for a wide range of remote environmental monitoring applications; including specific climate synoptic observation research and more general meteorology. For the application proposed in this thesis a cluster of the notional smart dust motes are configured to imitate discrete 'Radio Drop Sonde' elements of the wireless enabled monitoring system in use by meteorological research organisations worldwide. This cluster is modelled in software in order to establish the relative positions during the 'flight' ; the normal mode of deployment for the Drop Sonde is by ejection from an aeroplane into an upper-air zone of interest, such as a storm cloud. Therefore the underlying research question is, how to track a number of these independent, duplex wireless linked, free-flying monitoring devices in 3-dimensions and time (to give the monitored data complete spatio-temporal validity). This represents a significant practical challenge, the solution applied in this thesis was to generate 3-dimensional geometries using the only 'real-time' data available; the Radio Signal Strength Indicator (RSSI) data is generated through the 'normal' duplex wireless communications between motes. Individual RSSI values can be considered as a 'representation of the distance magnitude' between wireless devices; when collated into a spatio-temporal data-set it 'encodes' the relative, co-locational, 3-dimensional geometry of all devices in the cluster. The reconstruction, (or decoding), of the 3-dimensional geometries encoded in the spatio-temporal data-set is a complex problem that is addressed through the application of various algorithms. These include, Random Search, and optimisation algorithms, such as the Stochastic Hill-climber, and various forms of Evolutionary Algorithm. It was found that the performance of the geometric reconstruction could be improved through identification of salient aspects of the modelled environment, the result was heuristic operators. In general these led to a decrease in the time taken to reach a convergent solution or a reduction in the number of candidate search space solutions that must be considered. The software model written for this thesis has been implemented to generalise the fundamental characteristics of an optimisation algorithm and to incorporate them into a generic software framework; this then provides the common code to all model algorithms used.

The aim of this thesis is to identify the key roles of expatriates in a major Japanese MNE and factors influencing formation of their roles. It also examines to what extent expatriates have discretion in forming their roles. The thesis uses empirical data from 109 interviews and 5 years of action research (44 advisory board meetings and 144 Human Resource Management (HRM) workshops, 19 research sites in 9 countries and 17 additional meetings on specific topics) that enabled the researcher to carry out insightful and in-depth analysis with cross-national and multi-layer perspectives. The study applies organisational design theory to unveil the mechanisms of role formation, significantly expanding the understanding of these issues in Japanese business and the international business literature. The findings suggest that the process of role formation of expatriates can be explained by combining contingency theory and strategic choice theory in a framework that argues that the roles of expatriates are the result of a political process of organisational design (Child, 1997). This includes adaptation to the environment (Lawrence and Lorsch, 1967) but also the relationship between organisational agents and the environment in the process of strategic choice (Child, 1997). The major contribution of this study is to provide evidence that expatriates are not merely agents of HQs in international business as traditionally understood, but that their role is more complex and multifaceted. The study empirically identifies five key roles of expatriates - two more than previously identified in the literature - and unveils six contingency factors and two strategic choice factors influencing role formation. The thesis demonstrates that expatriates strategically select their roles, although internal and external factors can act either as enhancers or obstacles to their making of choices and role formation.

Ubiquitous computing systems aim to assist us as we go about our daily lives, whilst at the same time fading into the background so that we do not notice their presence. To do this they need to be able to sense their surroundings and infer context about the state of the world. Location has proven to be an important source of contextual information for such systems. If a device can determine its own location then it can infer its surroundings and adapt accordingly. Of particular interest for many ubiquitous computing systems is the ability to track people in indoor environments. This interest has led to the development of many indoor location systems based on a range of technologies including infra-red light, ultrasound and radio. Unfortunately existing systems that achieve the kind of sub-metre accuracies desired by many location-aware applications require large amounts of infrastructure to be installed into the environment. This thesis investigates an alternative approach to indoor pedestrian tracking that uses on-body inertial sensors rather than relying on fixed infrastructure. It is demonstrated that general purpose inertial navigation algorithms are unsuitable for pedestrian tracking due to the rapid accumulation of errors in the tracked position. In practice it is necessary to frequently correct such algorithms using additional measurements or constraints. An extended Kalman filteris developed for this purpose and is applied to track pedestrians using foot-mounted inertial sensors. By detecting when the foot is stationary and applying zero velocity corrections a pedestrian's relative movements can be tracked far more accurately than is possible using uncorrected inertial navigation. Having developed an effective means of calculating a pedestrian's relative movements, a localisation filter is developed that combines relative movement measurements with environmental constraints derived from a map of the environment. By enforcing constraints such as impassable walls and floors the filter is able to narrow down the absolute position of a pedestrian as they move through an indoor environment. Once the user's position has been uniquely determined the same filter is demonstrated to track the user's absolute position to sub-metre accuracy. The localisation filter in its simplest form is computationally expensive. Furthermore symmetry exhibited by the environment may delay or prevent the filter from determining the user's position. The final part of this thesis describes the concept of assisted localisation, in which additional measurements are used to solve both of these problems. The use of sparsely deployed WiFi access points is discussed in detail. The thesis concludes that inertial sensors can be used to track pedestrians in indoor environments. Such an approach is suited to cases in which it is impossible or impractical to install large amounts of fixed infrastructure into the environment in advance.

Poly(A)-binding proteins (PABPs) are important regulators of mRNA translation and stability. In mammals four cytoplasmic PABPs with a similar domain structure have been described - PABP1, tPABP, PABP4 and ePABP. The vast majority of research on PABP mechanism, function and sub-cellular localisation is however limited to PABP1 and little published work has explored the expression of PABP proteins. Here, I examine the tissue distribution of PABP1 and PABP4 in mouse and show that both proteins differ markedly in their expression at both the tissue and cellular level, contradicting the widespread perception that PABP1 is ubiquitously expressed. PABP4 is shown to be widely expressed though with an expression pattern distinct from PABP1, and thus may have a biological function in many tissues. I have shown that PABP4 associates with polysomes and described interactions between PABP4 and proteins important for PABP1-mediated translational activation suggesting that PABP4 plays a similar role in translational regulation. Translational inhibition is a common response to cell stress. Following certain cellular stresses e.g. arsenite, PABP1 localises to cytoplasmic stress granules, sites of mRNA storage. Here, I show that PABP4 is also a component of stress granules and have investigated the role of PABPs in stress granule formation. In contrast, I have shown that both PABP1 and PABP4 relocalise to the nucleus following UV irradiation in both human and mouse cell lines. In order to understand the how the UV-induced change in PABP localisation may be regulated, I have investigated the regulation of PABP nuclear export. I have found that accumulation of PABP proteins in the nucleus after UV coincides with an accumulation of poly(A)+ RNA, indicative of a block in mRNA export, an effect which has not been previously characterized. My working model is that nuclear export of PABPs may be dependent on mRNA export, inhibition of which leads to nuclear accumulation of PABPs after UV, which may in turn augment translational inhibition.

In recent years, advances in signal processing have led to small, low power, inexpensive Wireless Sensor Network (WSN). The signal processing in WSN is different from the traditional wireless networks in two critical aspects: firstly, the signal processing in WSN is performed in a fully distributed manner, unlike in traditional wireless networks; secondly, due to the limited computation capabilities of sensor networks, it is essential to develop an energy and bandwidth efficient signal processing algorithms. Target localisation and tracking problems in WSNs have received considerable attention recently, driven by the necessity to achieve higher localisation accuracy, lower cost, and the smallest form factor. Received Signal Strength (RSS) based localisation techniques are at the forefront of tracking research applications. Since tracking algorithms have been attracting research and development attention recently, prolific literature and a wide range of proposed approaches regarding the topic have emerged. This thesis is devoted to discussing the existing WSN-based localisation and tracking approaches. This thesis includes five studies. The first study leads to the design and implementation of a triangulation-based localisation approach using RSS technique for indoor tracking applications. The presented work achieves low localisation error in complex environments by predicting the environmental characteristics among beacon nodes. The second study concentrates on investigating a fingerprinting localisation method for indoor tracking applications. The proposed approach offers reasonable localisation accuracy while requiring a short period of offline computation time. The third study focuses on designing and implementing a decentralised tracking approach for tracking multiple mobile targets with low resource requirements. Despite the interest in target tracking and localisation issues, there are few systems deployed using ZigBee network standard, and no tracking system has used the full features of the ZigBee network standard. Tracking through the ZigBee is a challenging task when the density of router and end-device nodes is low, due to the limited communication capabilities of end-device nodes. The fourth study focuses on developing and designing a practical ZigBee-based tracking approach. To save energy, different strategies were adopted. The fifth study outlines designing and implementing an energy-efficient approach for tracking applications. This study consists of two main approaches: a data aggregation approach, proposed and implemented in order to reduce the total number of messages transmitted over the network; and a prediction approach, deployed to increase the lifetime of the WSN. For evaluation purposes, two environmental models were used in this thesis: firstly, real experiments, in which the proposed approaches were implemented on real sensor nodes, to test the validity for the proposed approaches; secondly, simulation experiments, in which NS-2 was used to evaluate the power-consumption issues of the two approaches proposed in this thesis.

In this work we investigate themes related to many-body systems in which multiple ground states are accessible, a condition known as frustration. Frustration can arise in a number of contexts, and we consider the consequences of this situation with some examples from condensed-matter physics. In some magnetic materials interactions between spins are such that no single spin configuration provides a unique ground state. In the class of frustrated magnets where the number of ground states is extensive, thermal fluctuations are strong even at temperatures significantly below the interaction strength. At such temperatures spins are highly correlated, and small perturbations may have profound consequences. In this thesis we provide an example of this. By considering classical n-component spins with nearest-neigbour exchange on a frustrated octahedral lattice we show that – in the limit where exchange interactions are large – the system is in a disordered, correlated phase where correlations have the form of a dipole field. This is termed a Coulomb phase. From this phase we induce an ordering transition, lifting the degeneracy with weak, additional short-range interactions. By studying the transition in the solvable limit of n → ∞, we discover that the transition has identical thermodynamics to that of a magnetic system interacting through long-range, dipolar forces. Finally, we provide a more apposite characterisation of the transition, where the high-temperature side of the transition is described through the fluctuations of solenoidal fields, and the ordering corresponds to a condensation of these fields. In a separate part of the thesis, we investigate the influence of disorder on frustrated lattices. We study a two-dimensional tight-binding model with nearest-neighbour hopping and on-site disorder. Restricting the allowed states to being those from the low-lying manifold of ground states, the disorder feeds through to act as effective disorder in the hopping terms, which decay algebraically with distance. The quasi-long range nature of this effective hopping leads to a situation in which the resultant single-particle eigenstates are critical, and we probe their behaviour numerically with a transfer matrix calculation.

LoRa is an emerging technology of low-power wide-area networks (LPWANs) operating on industrial, scientific and medical (ISM) bands to provide connectivity for Internet of Thing (IoT) devices. As the number of devices increases, the network suffers from scalability issues. Therefore, we design a cloud radio access network (C-RAN or Cloud-RAN) with multiple LoRa gateways to solve this problem. Furthermore, we develop novel algorithms to provide accurate localisation for LoRa devices. This thesis makes three new contributions to LoRa based communication and localisation system as follows. The first contribution is a compressive sensing-based algorithm to reduce the uplink bit rate between the gateways and the cloud server. The proposed novel compression algorithm can reduce the bandwidth usage for the fronthaul without decreasing LoRa packet delivery rates. Our evaluation shows that with four gateways up to 87.5% PHY samples can be compressed and 1.7x battery life for end devices can be achieved. The second contribution is a novel algorithm to improve the resolution of the radio signals for localisation. The proposed algorithm synchronises multiple non-overlapped communication channels by exploiting the unique features of the LoRa radio to increase the overall bandwidth. We evaluate its performance in an outdoor area of 100 m × 60 m, which shows a median error of 4.4 m, and a 36.2% error reduction compared to the baseline. The above approach improves the accuracy of outdoor localisation; however, it does not work for indoor localisation due to the increase of multiple radio propagation paths. Therefore, our third contribution is an improved super-resolution algorithm for indoor localisation. By exploiting both the original and the conjugate of the physical layer, the algorithm can resolve the multiple paths from multiple reflectors in clustered indoor environments. We evaluate its performance in an indoor area of 25 m × 15 m, which shows that a median error of 2.4 m can be achieved, which is 47.8% and 38.5% less than the baseline approach and the approach without using the conjugate information, respectively. Our evaluation also shows that, different to previous studies in Wi-Fi localisation systems that have significantly wider bandwidth, time-of-fight (ToF) estimation is less effective to LoRa localisation systems with narrowband radio signals.

Electrides are a unique class of ionic materials in which the anions are stoichiometrically replaced by localised electrons. This unique chemical structure confers a number of desirable properties. However, the majority of the electride crystals are temperature unstable making experimental examination of these materials difficult. Theoretical methods are not hindered by the practical problems afflicting the experimental approaches and, as such, present an ideal alternate route for the ongoing investigation of electrides.Density-functional theory (DFT) is used to conduct this theoretical investigation. We first explore the potential systematic errors associated with common density functionals when modelling a localised electron within a crystal void, which is the central characteristic of the electride crystals. Bare DFT is shown to excessively delocalise the interstitial electron, while use of continuum solvent models with DFT overly localises this electron. In the latter case, we find the excessive localisation phenomena is dependent only on the applied solvent correction and any electronicstructure method that uses a similar correction will exhibit the same errors.The alkali metal-ligand complexes, the building blocks of the electride crystals, are modelled and thermodynamic cycles constructed, highlighting the energy changes that occur when these complexes form. The ionisation potential of the alkali metal-ligand complexes is found to be consistently between 1 and 2 eV, regardless of the alkali metal or ligand molecule used. We propose this be used as a design criteria for future computational testing of potential electride-forming alkali metal-ligand complexes.DFT analysis of all of the known electride crystals (at the time) is conducted. As well as establishing a common ground from which to theoretically discuss the electrides (the first such study to do so), we identify the 'electride state' for all of the organic electride crystals. This state is associated with the localised electron and resides between the conduction and valence band in the band structure. By modifying the initial self-consistent field guess, we were able to find the first all-electron solutions for the magnetic states of the organic electrides. These magnetic states reproduced the expected anti-ferromagnetic behaviour, in some cases to a remarkable degree of accuracy.Finally, we computationally apply pressure to the simplest organic electride, Cs+(15-crown-5)2e-. We find that the magnetic properties of the electride change significantly upon compression, eventually becoming ferromagnetic. This switch from an anti-ferromagnetic to ferromagnetic ground state, termed piezomagnetism, means that Cs+(15-crown-5)2e-, and potentially other electrides, can develop a spontaneous magnetic moment under pressure. Piezomagnetism is a rare property that has just as many potential applications as the well known piezoelectric materials. The range of pressure computationally applied is easily accessible to modern experimental techniques and this result should be reasonably easy to verify experimentally.

Embedded sensing aims to use low-cost computing, sensing and communication components to realise various sensing tasks. Embedded sensing has been successfully used in different applications. Large amounts of sensing data contain abundant information, but create huge overheads for the resource-limited embedded nodes. Furthermore, interference from other sources also brings noise, which decreases the sensing performance. In this thesis, we apply Sparse Approximation-based Classification method (SAC) and electronically switched directional (ESD) antennas to address the challenges of the limited amount of resources in embedded systems and interference. Three different problems are addressed. The first problem is to reduce the overhead of real-time classification on Acoustic Sensor Networks (ASNs). The main challenges of in-network classification in ASNs include effective feature selection, intensive computation requirement and high noise levels. To address these challenges, we propose a sparse representation based featureless, low computational cost, and noise resilient framework for in-network classification in ASNs, which makes the computation feasible to be performed on resource constrained ASN platforms. The second problem is to make radio-based device-free activity recognition robust to radio frequency interference (RFI). Device-free activity recognition has the advantage that it does not have the privacy concern of using cameras and the subjects do not have to carry a device on them. Recently, it has been shown that channel state information (CSI) can be used for activity recognition in a device-free setting. We investigate the impact of RFI on device-free CSI-based location-oriented activity recognition. We propose a number of SAC-based fusion methods to mitigate the impact of RFI and improve the location-oriented activity recognition performance. The third problem is to reduce the impact of multipath propagation for radio tomographic imaging (RTI) . RTI enables device-free localisation of people and objects in many challenging environments and situations. However, the localisation accuracy of RTI suffers from complicated multipath propagation behaviours in radio links. We propose to use inexpensive and energy efficient ESD antennas to improve the localisation accuracy of RTI. We implement a directional RTI system to understand how directional antennas can be used to improve RTI localisation accuracy.

Global Navigation Satellite Systems (GNSS) are increasingly being relied upon in many applications. Reference stations provide corrections to errors inherent in GNSS processing, allowing GNSS to be used in more applications. The GNSS satellite signals are relatively weak and receivers are susceptible to Radio-Frequency Interference (RFI). To maintain the integrity of these reference stations any RFI must be detected and localised quickly. The research presented in this thesis investigates the detection and localisation of RFI using a sensor network. The first part of this thesis investigates RFI detection. For stationary receivers located in a stable environment, variations in the Carrier-to-Noise Density Ratio (C/No) can be used for detection. Weaker RFI can be detected if variations due to multipath are removed as they repeat with each satellite groundtrack. Issues associated with using the Automatic-Gain-Control (AGC) for RFI detection are also investigated. The drift in the AGC due to temperature is characterised and it could be reduced using a gain/temperature model, allowing the AGC to be used for detecting weaker RFI. The second part of this thesis investigates RFI localisation. An analysis using Dilution-of-Precision (DOP) showed that the Received-Signal-Strength (RSS) technique has potential. RSS performance was evaluated using simulations and real measurements and was found to suffer degradation due to the presence of ground reflections, resulting in the concluding that RSS is not appropriate. Time-Difference-Of-Arrival (TDOA) is another potential localisation method. Different aspects that affect TDOA were investigated, including time synchronization and effect of GNSS satellite cross-correlations. It was found that a number of time-delay measurements could be made before the timing from jammed GPS timing receivers degraded significantly, and that the GNSS satellite cross-correlation peaks make detecting and localising weaker RFI difficult. The explored C/No and AGC techniques are suitable for implementation into a sensor network and could detect weaker RFI using methods proposed in this thesis. For RFI localisation, TDOA was found superior to the RSS but some issues were found concerning weak RFI. The effectiveness of TDOA was demonstrated in a prototype system with real RFI and performance could be improved through an offline time synchronisation technique.

This thesis proposes two acoustic localisation techniques that are accurate in Non-Line-of-Sight (NLoS) conditions and system implementation of the proposed techniques. Such conditions can cause positive bias errors, namely NLoS errors, in the measured Time-of-Arrivals (ToAs) of first-arrival signals received by microphones and thus reduce the positioning accuracy. The primary issue of the thesis is to precisely estimate and correct the NLoS errors by modelling the received first-arrival signals. The first proposed technique uses multiple on-ground microphones to locate a sound source. The proposed technique approximately estimates and corrects the NLoS errors based on an initial guess of the sound source position and a map. The localisation is then achieved by iteratively correcting the ToAs and updating the sound source location. The strength of the proposed technique is that its accuracy is not notably affected by small or known obstacles. The proposed technique is implemented into two localisation systems of controlled and uncontrolled sound sources. The performance of the proposed technique is investigated by its comparison with three other time-based localisation techniques in series of experiments and simulations, showing at least 10% improvement by the proposed technique under various background noise levels. The second proposed technique localises a sound source using a single on-ground microphone subject to an assumption of a single diffraction in the first-arrival signal. To predict the angular and radial coordinates of the sound source relative to the diffraction point, a new magnitude delay frequency profile is proposed. The profile can be estimated by applying the uniform geometrical theory of diffraction and be extracted from measured signals using a derived formulation. Similar to the first technique, the second proposed technique estimates the measured delay of the first-arrival signal for computing the radial coordinate. The angular coordinate is then obtained by matching the estimated and measured profiles at the measured delay. A key achievement of the second proposed technique is enabling NLoS localisation using only one microphone without any time-consuming pre-measurement. This technique is implemented into a localisation system of a controlled sound source and validated experimentally with three different sound sources and under two background noise levels.