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A Survey of Deep Learning Applications to Autonomous Vehicle Control
No full textDesigning a controller for autonomous vehicles capable of providing adequate performance in all driving scenarios is challenging due to the highly complex environment and inability to test the system in the wide variety of scenarios which it may encounter after deployment. However, deep learning methods have shown great promise in not only providing excellent performance for complex and non-linear control problems, but also in generalising previously learned rules to new scenarios. For these reasons, the use of deep learning for vehicle control is becoming increasingly popular. Although important advancements have been achieved in this field, these works have not been fully summarised. This paper surveys a wide range of research works reported in the literature which aim to control a vehicle through deep learning methods. Although there exists overlap between control and perception, the focus of this paper is on vehicle control, rather than the wider perception problem which includes tasks such as semantic segmentation and object detection. The paper identifies the strengths and limitations of available deep learning methods through comparative analysis and discusses the research challenges in terms of computation, architecture selection, goal specification, generalisation, verification and validation, as well as safety. Overall, this survey brings timely and topical information to a rapidly evolving field relevant to intelligent transportation systems
A methodology to account for dynamic variability in micro-vibration analysis of satellites
No full textNominal operability of satellites can be significantly affected by low level vibrations in the range of micro-g generated by on board mechanisms. These are referred to as micro-vibrations and can considerably jeopardise the regular functioning of very high precision sensors. Hence, it is essential to study their features in terms of characterisation and analysis, which are greatly affected by structural uncertainties due, among other causes, to the manufacturing and assembly tolerances. In this thesis the variability of micro-vibrations arising from structural uncertainties is targeted, through the implementation of a macroscopic approach that is able to take into account different sources of structural uncertainties. In particular the work done in this doctorate is split into two main areas. First the characterisation of micro-vibration sources is studied; these include all the devices on board the spacecraft that can generate micro-vibrations. A methodology to investigate the effects of manufacturing defects on the dynamics of reaction wheels is described, by focusing on the frequency domain representation of their disturbance. Through this approach, it is possible to define a group of nominally-identical devices by means of a single disturbance input matrix. Such achievement can be beneficial in space applications as it allows an easier assessment of micro-vibrations on the spacecraft. Second, the issue of structural uncertainty is addressed in terms of transmission path from the source to the receiver. The focus here is shifted towards the development of an analysis methodology that can target the issue of structural uncertainties by satisfying the stringent computational requirements for aerospace applications. In particular, the main achievement obtained in this thesis stays in the development of an uncertainty quantification methodology that can be used to provide an estimation of perturbation parameters used in the Craig-Bampton Stochastic Method
Gut commensal bacteria show beneficial properties as wildlife probiotics
No full textProbiotics represent a non-invasive, environmentally-friendly alternative to reduce infectious diseases in wildlife species. Our aim was to evaluate the potential of typical gut commensals, such as lactic acid bacteria (LAB), as wildlife probiotics. The selected LAB were isolated from European badgers (Meles meles); a wildlife reservoir of bovine tuberculosis, and comprised four different genera: Enterococcus; Weissella; Pediococcus; and Lactobacillus. The enterococci displayed a phenotype and genotype that correlate with the production of antibacterial peptides and stimulation of antiviral responses. However, these isolates carry virulence and antibiotic resistance genes. Weissella showed some anti-mycobacterial activity due to their ability to produce lactate and ethanol. Interestingly, lactobacilli and pediococci modulated pro-inflammatory phagocytic responses that associate with protection against pathogens; and these responses agreed with the presence of immunomodulatory markers in their genomes. Although both lactobacilli and pediococci showed tolerance to antibiotics, this resistance was naturally acquired and almost all isolates possessed a strong phylogenetic relationship with isolates from food and healthy animals. Our results show that LAB display probiotic benefits that depend on the genera. Lactobacilli and pediococci are probably the most interesting candidates as probiotics against infectious diseases in wildlife because of their food-grade status and ability to modulate protective innate immune responses
The Future of EU Development Policy Post-2020
No full textUnder the current proposals, the EU development cooperation budget would increase by 30%. This paper explores how this potential increase is designed to assist the EU in consolidating its international identity in line with the aims of the Global Strategy (EUGS) by better aligning the money in the development budget to the global ambitions of the EU. This has reignited concerns that this represents further politicisation of the development activities of the EU beyond the Treaty commitment to poverty reduction and once again highlights the tension between development goals and broader strategic goals. This paper explores this tension between development and strategic goals in what is clearly a moving target area. Comparing how the vision for EU development policy has evolved between the 2006 and 2017 Consensus’ on Development provides the context for a comparison to broader vision for external action set out in the EU’s Global Strategy. The paper then explores the proposed budget reforms in light of this comparison highlighting the implications for the EU as a development actor. It shows how discussions around the size of the EU budget coincide with Brexit and the renegotiation of the EU’s relationship with a key group of developing countries, the ACP. It shows that the future negotiations will focus on the overall amount of the EU development budget, how the budget will be used and where – decisions that will shine a light onto the priorities of the EU as a development actor
Vectorial birefringence imaging by optical coherence microscopy for assessing fibrillar microstructures in the cornea and limbus
No full textThe organization of fibrillar tissue on the micrometer scale carries direct implications
for health and disease but remains difficult to assess in vivo. Polarization-sensitive optical
coherence tomography measures birefringence, which relates to the microscopic arrangement
of fibrillar tissue components. Here, we demonstrate a critical improvement in leveraging this
contrast mechanism by employing the improved spatial resolution of focus-extended optical
coherence microscopy (1.4 μm axially in air and 1.6 μm laterally, over more than 70 μm depth of
field). Vectorial birefringence imaging of sheep cornea ex vivo reveals its lamellar organization
into thin section
Phenomenological-contextualist accounts of the experience of obsessions and compulsions: a theoretical thematic analysis study
No full textThe experience of obsessions and compulsions in the form of the diagnostic construct OCD has been widely researched. The majority of this research adopts a medical model perspective underpinned by an objectivist philosophy which does not account for the constitutive role relational contexts play in the experience of obsessions and compulsions. More recently, research has begun to attend more explicitly to the relational experience of OCD by investigating the impact this has on the diagnosed individuals’ relationships with others. However, such research is scarce. Therefore, this study aimed to build on this knowledge, by exploring the intersubjective understanding of obsessions and compulsions from a standpoint that is inherently relational. This was achieved through theoretical thematic analysis, whereby the intersubjective experience of obsessions and compulsions was explored from the vantage point of intersubjectivity systems theory (IST). Semi-structured interviews were conducted with six participants, leading to the construction of four overarching themes: “emotional unavailability in the family system”, “sense of separation leading to relational disconnection”, “shielding the self because hell is other people” and “finding a place of safety”. The findings suggest that relational disconnection and emotional isolation are a significant source of distress to individuals affected
Minimizing non-radiative recombination losses in perovskite solar cells
No full textPhotovoltaic solar cells based on metal halide perovskites have gained considerable attention over the past decade because of their potentially low production cost, earth-abundant raw materials, ease of fabrication and ever-increasing power conversion efficiencies of up to 25.2%. This type of solar cells offers the promise of generating electricity at a more competitive unit price than traditional fossil fuels by 2035. Nevertheless, the best research cell efficiencies are still below the theoretical limit defined by the Shockley-Queissier theory owing to the presence of non-radiative recombination losses. In this Review, we analyse the predominant pathways that contribute to non-radiative recombination losses in perovskite solar cells, and evaluate their impact on device performance. We then discuss how non-radiative recombination losses can be estimated through reliable characterization techniques, and highlight some notable advances in mitigating these losses, which hint at pathways towards defect-free perovskite solar cells. Finally, we outline directions for future work that will push the efficiency of perovskite solar cells towards the radiative limit
The impact of servitization and digitization on productivity and profitability of the firm: a systematic approach
No full textWe propose a new systematic method to answer the research question: ‘What is the financial and economic
impact of servitizing the firm, digitising the firm, and combined servitization and digitization
strategy?’ Our method quantifies servitization, digitization and their synergy by analysing their relationship with firm financial and economic outcomes. The method is applied to the British publishing
industry. Using text-mining and econometric analysis of secondary data, 258 UK book publishers (93%
of the market share) are analysed over a period of 10 years (1,508 observations). Firms are categorised
as servitized (S-firms), digitized (D-firms), digitized and servitized (DS-firms) and pure (P-firms) that are
neither servitized nor digitized (control group). We detect no significant difference in terms of productivity
and profitability between P-firms and D-firms. Although we find evidence of a servitization paradox,
both S-firms and DS-firms show greater productivity than P-firms. Profitability of DS-firms is
greater than that of P-firms, but profitability of S-firms is lower than that of P-firms. The research
improves on the existing methodology employed to examine the impact of servitizing or digitising
the firm and provides a means to measure how servitization and digitization impact on the productivity
and profitability of a firm within a specific context
Stochastic resonance for spectrum sensing of multi-carrier modulated waveforms
No full textSpectrum sensing has received abundant attention from the research community. However, with sensing scenarios becoming increasingly complex, existing spectrum sensing schemes can hardly meet the demand for fast, accurate spectrum sensing, particularly in the very low signal-to-noise ratio (SNR) range, without dramatically increasing system complexity and the need for precise information about signal and noise. Furthermore, the widespread adoption of multicarrier modulation in various existing and evolving standards is driving efforts to develop a robust and practical solution for multicarrier signal spectrum sensing. The main challenges identified in lieu of changing spectrum scenarios are detection in low SNR, high accuracy, low computational and sample complexity, and possible operation without the knowledge of the primary user (PU) signal and channel.
Stochastic Resonance (SR) is a phenomenon in which a signal too weak to cross the detection threshold becomes detectable in a nonlinear system with the addition of noise. This research considers the application of SR to sense multi-frequency/multi-carrier signals. The effect of the SR receiver has never been verified for multi-carrier signals, which is a popular modulation system in various existing and evolving standards. The thesis provides an understanding of how and why the SR effect for multi-frequency signals differs from the SR effect for single frequency signals. Special features such as ghost resonance, multi-resonance and doubly SR are demonstrated with simulations. A novel method to identify ghost resonance is proposed and the relationship of noise intensity and frequencies of the driving signal is derived. SR for multi-frequency signals is quantified in terms of the SNR.
In the presented research, SR is used as a pre-processing technique to enhance SNR prior to the detector, which significantly improves spectrum sensing performance. The two main contributions in this part of the research are (i) A novel algorithm for dynamic determination of SR system parameters and noise intensity, which results in maximum SNR; (ii) An SR-based sensing method particularly tailored to give near-optimal performance for multi-carrier signals by using the multi-taper spectral estimate (MTSE) method. A simple Fourier transform-based method is also evaluated as a computationally light alternative to MTSE. The FFT-based method combined with (i) provides near-optimal performance for single-carrier modulated schemes. The performance is evaluated in low SNR, flat/frequency selective fading,
iii
shadowing, interference and time/frequency offset. The results show that by using SR pre-processing, the performance of energy-based detection (ED) can be significantly improved. The proposed method is also evaluated in cooperative sensing scenarios. The results show that the proposed SR-ED with a basic cooperative mechanism can match the performance of ED-based cooperative sensing with optimal fusion. The proposed method has several distinctive features including low latency, high accuracy, reasonable computational complexity, robustness to low SNR, robustness to flat/frequency selective fading, robustness to noise/channel uncertainty. It also requires no prior knowledge of the PU signal
How to extend the chart of nuclides?
No full textIn the past 85 years the number of known nuclides
increased by more than a factor of ten, resulting in 4000
presently known isotopes of 118 elements. This considerable progress we owe to the discovery of new reaction types along with the development of powerful accelerators and experimental techniques for separation and identification of reaction products. Model predictions indicate that still about
4000 further nuclides are waiting for their discovery. The vastest unexplored territory is located on the neutron-rich side in the upper half of the chart of nuclides and hides the answers to some of the most fundamental questions of nuclear physics like the limits of nuclear stability, element
synthesis in the universe or stellar evolution. The access to these nuclei is presently limited by available beam intensities and/or the lack of appropriate methods for their production and identification. The latter concerns particularly new neutron-rich isotopes of transuranium and superheavy
elements. To extend this area, the hope is presently based on multinucleon transfer reactions and on the application of fusion reactions with radioactive ion beams. But how promising are these approaches? Based on a survey of present-day knowledge, we will treat the questions where we currently are
on our journey towards new territory on the chart of nuclides, how the chances are to gain new territory in the future and which challenges we will have to face
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