A Bayesian formulation of search, control and the exploration/exploitation trade-off

A new approach to optimisation is introduced based on a precise probabilistic statement of what is ideally required of an optimisation method. It is convenient to express the formalism in terms of the control of a stationary environment. This leads to an objective function for the controller which unifies the objectives of exploration and exploitation, thereby providing a quantitative principle for managing this trade-off. This is demonstrated using a variant of the multi-armed bandit problem. This approach opens new possibilities for optimisation algorithms, particularly by using neural network or other adaptive methods for the adaptive controller. It also opens possibilities for deepening understanding of existing methods. The realisation of these possibilities requires research into practical approximations of the exact formalism.

Technology sourcing versus technology exploitation:An analysis of US foreign direct investment flows

The traditional paradigm of foreign direct investment (FDI) suggests that FDI is undertaken principally to exploit some firm-specific advantage in a foreign country which provides a locational advantage to the investor. However, recent theoretical work suggests a model of FDI in which the motivation is not to exploit existing technological advantages in a foreign country, but to access such technology and transfer it from the host economy to the investing multinational corporation via spillover effects. This paper tests the technology sourcing versus technology exploiting hypotheses for a panel of sectoral FDI flows between the United States and major OECD nations over a 15 year period. The research makes use of Patel and Vega's (Research Policy, 28, 145-55, 1999) taxonomy of sectors which are likely a priori to exhibit technology sourcing and exploiting behaviour respectively. While there is evidence that FDI flows into the United States are attracted to R and D intensive sectors, very little support is found for the technology sourcing hypothesis either for inward or outward FDI flows. The results suggest that, in aggregate, firm-specific 'ownership' effects remain powerful determinants of FDI flows.

Exploitation of fibre characteristics in temperature sensing and radio-over-fibre applications

The development of sensing devices is one of the instrumentation fields that has grown rapidly in the last decade. Corresponding to the swift advance in the development of microelectronic sensors, optical fibre sensors are widely investigated because of their advantageous properties over the electronics sensors such as their wavelength multiplexing capability and high sensitivity to temperature, pressure, strain, vibration and acoustic emission. Moreover, optical fibre sensors are more attractive than the electronics sensors as they can perform distributed sensing, in terms of covering a reasonably large area using a single piece of fibre. Apart from being a responsive element in the sensing field, optical fibre possesses good assets in generating, distributing, processing and transmitting signals in the future broadband information network. These assets include wide bandwidth, high capacity and low loss that grant mobility and flexibility for wireless access systems. Among these core technologies, the fibre optic signal processing and transmission of optical and radio frequency signals have been the subjects of study in this thesis. Based on the intrinsic properties of single-mode optical fibre, this thesis aims to exploit the fibre characteristics such as thermal sensitivity, birefringence, dispersion and nonlinearity, in the applications of temperature sensing and radio-over-fibre systems. By exploiting the fibre thermal sensitivity, a fully distributed temperature sensing system consisting of an apodised chirped fibre Bragg grating has been implemented. The proposed system has proven to be efficient in characterising grating and providing the information of temperature variation, location and width of the heat source applied in the area under test.To exploit the fibre birefringence, a fibre delay line filter using a single high-birefringence optical fibre structure has been presented. The proposed filter can be reconfigured and programmed by adjusting the input azimuth of launched light, as well as the strength and direction of the applied coupling, to meet the requirements of signal processing for different purposes in microwave photonic and optical filtering applications. To exploit the fibre dispersion and nonlinearity, experimental investigations have been carried out to study their joint effect in high power double-sideband and single-sideband modulated links with the presence of fibre loss. The experimental results have been theoretically verified based on the in-house implementation of the split-step Fourier method applied to the generalised nonlinear Schrödinger equation. Further simulation study on the inter-modulation distortion in two-tone signal transmission has also been presented so as to show the effect of nonlinearity of one channel on the other. In addition to the experimental work, numerical simulations have also been carried out in all the proposed systems, to ensure that all the aspects concerned are comprehensively investigated.

Urban ecosystems – tapping the human resource

In order to take an interest in environmental issues, people need an idea of what ‘the environment’ is, and to have access to something worth caring about. In the UK, around 90% of us already live in towns or cities, and by 2030, around 60% of the world’s population will live in urban areas. But without a vocal set of ‘owners’, public land such as parks and allotments can easily be lost. The majority of the UK's ‘natural’ areas have historically been created, managed or modified by humans. and we should appreciate urban habitats just as much as pristine reserves for the ecosystem services they provide. In particular, scruffy and overlooked brownfield sites can be amazing refugia for insect and plant species which can no longer persist in a countryside dominated by industrialised agriculture.

Exploitation of multilayer coatings for infrared surface plasmon resonance fiber sensors

We demonstrate surface plasmon resonance (SPR) fiber devices based upon ultraviolet inscription of a grating-type structure into both single-layered and multilayered thin films deposited on the flat side of a lapped D-shaped fiber. The single-layered devices were fabricated from germanium, while the multilayered ones comprised layers of germanium, silica, and silver. Some of the devices operated in air with high coupling efficiency in excess of 40 dB and an estimated index sensitivity of Delta lambda/Delta n = 90 mn from 1 to 1.15 index range, while others provided an index sensitivity of Delta lambda/Delta n = 6790 mn for refractive indices from 1.33 to 1.37. (C) 2009 Optical Society of America

Shaping strategic action through the rhetorical construction and exploitation of ambiguity

This paper extends existing understandings of how actors' constructions of ambiguity shape the emergent process of strategic action. We theoretically elaborate the role of rhetoric in exploiting strategic ambiguity, based on analysis of a longitudinal case study of an internationalization strategy within a business school. Our data show that actors use rhetoric to construct three types of strategic ambiguity: protective ambiguity that appeals to common values in order to protect particular interests, invitational ambiguity that appeals to common values in order to invite participation in particular actions, and adaptive ambiguity that enables the temporary adoption of specific values in order to appeal to a particular audience at one point in time. These rhetorical constructions of ambiguity follow a processual pattern that shapes the emergent process of strategic action. Our findings show that (1) the strategic actions that emerge are shaped by the way actors construct and exploit ambiguity, (2) the ambiguity intrinsic to the action is analytically distinct from ambiguity that is constructed and exploited by actors, and (3) ambiguity construction shifts over time to accommodate the emerging pattern of actions.

Media, ecology and conservation:using the media to protect the world's wildlife and ecosystems

The second book in The Converging World series, Media, Ecology and Conservation focuses on global connectivity and the role of new digital and traditional media in bringing people together to protect the world's endangered wildlife and conserve fragile and threatened habitats. New media offers opportunities for like-minded individuals, community groups, businesses and public organisations to learn and work cooperatively for the good of all species. One of the key themes of this book explores the important issue of how new information and communication technologies mediate the natural world, and our understanding of our place in it. By exploring the role of film, television, video, photography and the internet in animal conservation in the USA, India, Africa, Australia and the United Kingdom John Blewitt investigates the politics of media representation surrounding important controversies such as the trade in bushmeat, whaling and habitat destruction. The work and achievements of media/conservation activists are located within a cultural framework that simultaneously loves nature, reveres animals but too often ignores the uncomfortable realities of species extinction and animal cruelty.

Dynamic client portfolios as sources of ambidexterity:exploration and exploitation within and across client relationships

This paper explains how dynamic client portfolios can be a source of ambidexterity (i.e., exploration and exploitation) for knowledge-intensive firms (KIFs). Drawing from a unique qualitative dataset of firms in the global reinsurance market, we show how different types of client relationships underpin a dynamic client portfolio and become a source of ambidexterity for a KIF. We develop a process model to show how KIFs attain knowledge by segmenting their client portfolios, use that knowledge to explore and exploit within and across their client relationships, and dynamically adjust their client portfolios over time. Our study contributes to the literature on external sources of ambidexterity and dynamic management of client knowledge within KIFs.

A study of the exploitation of the properties of natural rubber in tyres

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

Geographical variation in carbon dioxide fluxes from soils in agro-ecosystems and its implications for life-cycle assessment

1. Exchange of carbon dioxide (CO2) from soils can contribute significantly to the global warming potential (GWP) of agro-ecosystems. Due to variations in soil type, climatic onditions and land management practices, exchange of CO2 can differ markedly in different geographical locations. The food industry is developing carbon footprints for their products necessitating integration of CO2 exchange from soils with other CO2 emissions along the food chain. It may be advantageous to grow certain crops in different geographical locations to minimize CO2 emissions from the soil, and this may provide potential to offset other emissions in the food chain, such as transport. 2. Values are derived for the C balance of soils growing horticultural crops in the UK, Spain and Uganda. Net ecosystem production (NEP) is firstly calculated from the difference in net primary production (NPP) and heterotrophic soil respiration (Rh). Both NPP and Rh were estimated from intensive direct field measurements. Secondly, net biome production (NBP) is calculated by subtracting the crop biomass from NEP to give an indication of C balance. The importance of soil exchange is discussed in the light of recent discussions on carbon footprints and within the context of food life-cycle assessment (LCA). 3. The amount of crop relative to the biomass and the Rh prevailing in the different countries were the dominant factors influencing the magnitude of NEP and NBP. The majority of the biomass for lettuce Lactuca sativa and vining peas Pisum sativum, was removed from the field as crop; therefore, NEP and NBP were mainly negative. This was amplified for lettuces grown in Uganda (-16·5 and -17 t C ha-1 year-1 compared to UK and Spain -4·8 to 7·4 and -5·1 to 6·3 t C ha-1 year-1 for NEP and NBP, respectively) where the climate elevated Rh. 4. Synthesis and applications. This study demonstrates the importance of soil emissions in the overall life cycle of vegetables. Variability in such emissions suggests that assigning a single value to food carbon footprints may not be adequate, even within a country. Locations with high heterotrophic soil respiration, such as Spain and Uganda (21·9 and 21·6 t C ha-1 year-1, respectively), could mitigate the negative effects of climate on the C costs of crop production by growth of crops with greater returns of residue to the soil. This would minimize net CO2 emissions from these agricultural ecosystems.

Improving brain drug targeting through exploitation of the nose-to-brain route:a physiological and pharmacokinetic perspective

With an ageing population and increasing prevalence of central-nervous system (CNS) disorders new approaches are required to sustain the development and successful delivery of therapeutics into the brain and CNS. CNS drug delivery is challenging due to the impermeable nature of the brain microvascular endothelial cells that form the blood-brain barrier (BBB) and which prevent the entry of a wide range of therapeutics into the brain. This review examines the role intranasal delivery may play in achieving direct brain delivery, for small molecular weight drugs, macromolecular therapeutics and cell-based therapeutics, by exploitation of the olfactory and trigeminal nerve pathways. This approach is thought to deliver drugs into the brain and CNS through bypassing the BBB. Details of the mechanism of transfer of administrated therapeutics, the pathways that lead to brain deposition, with a specific focus on therapeutic pharmacokinetics, and examples of successful CNS delivery will be explored. © 2014 Bentham Science Publishers.

The evolution, development and exploitation of SIALON materials

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT