Machine Learning for Adaptive Computer Game Opponents

This thesis investigates the use of machine learning techniques in computer games to create a computer player that adapts to its opponent's game-play. This includes first confirming that machine learning algorithms can be integrated into a modern computer game without have a detrimental effect on game performance, then experimenting with different machine learning techniques to maximize the computer player's performance. Experiments use three machine learning techniques; static prediction models, continuous learning, and reinforcement learning. Static models show the highest initial performance but are not able to beat a simple opponent. Continuous learning is able to improve the performance achieved with static models but the rate of improvement drops over time and the computer player is still unable to beat the opponent. Reinforcement learning methods have the highest rate of improvement but the lowest initial performance. This limits the effectiveness of reinforcement learning because a large number of episodes are required before performance becomes sufficient to match the opponent

Measuring time preferences

We review research that measures time preferences—i.e., preferences over intertemporal tradeoffs. We distinguish between studies using financial flows, which we call “money earlier or later” (MEL) decisions and studies that use time-dated consumption/effort. Under different structural models, we show how to translate what MEL experiments directly measure (required rates of return for financial flows) into a discount function over utils. We summarize empirical regularities found in MEL studies and the predictive power of those studies. We explain why MEL choices are driven in part by some factors that are distinct from underlying time preferences.National Institutes of Health (NIA R01AG021650 and P01AG005842) and the Pershing Square Fund for Research in the Foundations of Human Behavior

Stability or renewal : the judicialisation of representative democracy in American and German constitutionalism

This thesis examines how American and German constitutionalism, as shaped by the U.S. Supreme Court and the German Constitutional Court (Bundesverfassungsgericht), have mediated the tension between threats to stability and the imperative of renewal through occasional or constant interventions in their democratic processes. To do this, it primarily assesses the 1960s U.S. reapportionment cases and the European Parliament electoral threshold cases of 2011 and 2014. It also considers the ideas of four thinkers, theorists and jurists who have wrestled with the dilemma of how to maintain the bond between citizen and state: Ernst-Wolfgang Böckenförde, Hannah Arendt, Thomas Jefferson and Alexis de Tocqueville. Stability and renewal represent the twin orientation points for constitutionalism and the courts against which they must adjust to possible democratic threats, or new political and social forces in need of recognition. Threats to the state can emerge either from a surfeit of illiberal views in politics and society aimed at destroying an existing constitutional order, or when democratic channels become starved of new opinions through the constitutional or unconstitutional exclusion of voters and parties. A distinctive feature of the approach taken is the conceptual division between the ‘legal/institutional’ space in which the Supreme Court and Bundesverfassungsgericht interpret constitutional meaning, and the ‘civic space’ in which citizens accept or reject constitutional meaning. One central question is how American and German constitutionalism, and the U.S. Supreme Court and Bundesverfassungsgericht shape and influence the vital civic space that is integral to the democratic relationship between citizen and state, and the survival of the state itself. Ultimately it is concluded that without acceptance of the importance of law and constitutionalism by citizens in the civic space, the influence of the Supreme Court and the Bundesverfassungsgericht becomes purely institutional and effectively consigned to the courtroom

Adaptive foveated single-pixel imaging with dynamic super-sampling

As an alternative to conventional multi-pixel cameras, single-pixel cameras enable images to be recorded using a single detector that measures the correlations between the scene and a set of patterns. However, to fully sample a scene in this way requires at least the same number of correlation measurements as there are pixels in the reconstructed image. Therefore single-pixel imaging systems typically exhibit low frame-rates. To mitigate this, a range of compressive sensing techniques have been developed which rely on a priori knowledge of the scene to reconstruct images from an under-sampled set of measurements. In this work we take a different approach and adopt a strategy inspired by the foveated vision systems found in the animal kingdom - a framework that exploits the spatio-temporal redundancy present in many dynamic scenes. In our single-pixel imaging system a high-resolution foveal region follows motion within the scene, but unlike a simple zoom, every frame delivers new spatial information from across the entire field-of-view. Using this approach we demonstrate a four-fold reduction in the time taken to record the detail of rapidly evolving features, whilst simultaneously accumulating detail of more slowly evolving regions over several consecutive frames. This tiered super-sampling technique enables the reconstruction of video streams in which both the resolution and the effective exposure-time spatially vary and adapt dynamically in response to the evolution of the scene. The methods described here can complement existing compressive sensing approaches and may be applied to enhance a variety of computational imagers that rely on sequential correlation measurements.Comment: 13 pages, 5 figure

Probing the Evaporation Dynamics of Ethanol/Gasoline Biofuel Blends Using Single Droplet Manipulation Techniques

Peer reviewedPublisher PD

Automated determination of auroral breakup during the substorm expansion phase using all sky imager data

This technique paper describes a novel method for quantitatively and routinely identifying auroral breakup following substorm onset using the Time History of Events and Macroscale Interactions During Substorms (THEMIS) all-sky imagers (ASIs). Substorm onset is characterised by a brightening of the aurora that is followed by auroral poleward expansion and auroral breakup. This breakup can be identified by a sharp increase in the auroral intensity i(t) and the time derivative of auroral intensity i'(t). Utilising both i(t) and i'(t) we have developed an algorithm for identifying the time interval and spatial location of auroral breakup during the substorm expansion phase within the field of view of ASI data based solely on quantifiable characteristics of the optical auroral emissions. We compare the time interval determined by the algorithm to independently identified auroral onset times from three previously published studies. In each case the time interval determined by the algorithm is within error of the onset independently identified by the prior studies. We further show the utility of the algorithm by comparing the breakup intervals determined using the automated algorithm to an independent list of substorm onset times. We demonstrate that up to 50% of the breakup intervals characterised by the algorithm are within the uncertainty of the times identified in the independent list. The quantitative description and routine identification of an interval of auroral brightening during the substorm expansion phase provides a foundation for unbiased statistical analysis of the aurora to probe the physics of the auroral substorm as a new scientific tool for aiding the identification of the processes leading to auroral substorm onset

Foundations of plasma standards

The field of low-temperature plasmas (LTPs) excels by virtue of its broad intellectual diversity, interdisciplinarity and range of applications. This great diversity also challenges researchers in communicating the outcomes of their investigations, as common practices and expectations for reporting vary widely in the many disciplines that either fall under the LTP umbrella or interact closely with LTP topics. These challenges encompass comparing measurements made in different laboratories, exchanging and sharing computer models, enabling reproducibility in experiments and computations using traceable and transparent methods and data, establishing metrics for reliability, and in translating fundamental findings to practice. In this paper, we address these challenges from the perspective of LTP standards for measurements, diagnostics, computations, reporting and plasma sources. This discussion on standards, or recommended best practices, and in some cases suggestions for standards or best practices, has the goal of improving communication, reproducibility and transparency within the LTP field and fields allied with LTPs. This discussion also acknowledges that standards and best practices, either recommended or at some point enforced, are ultimately a matter of judgment. These standards and recommended practices should not limit innovation nor prevent research breakthroughs from having real-time impact. Ultimately, the goal of our research community is to advance the entire LTP field and the many applications it touches through a shared set of expectations

Visions for a walking and cycling focussed urban transport system

Walking and cycling can make a considerable contribution to sustainable transport goals, building healthier and more sustainable communities and contributing to traffic and pollution reduction. There have been many national and local initiatives to promote walking and cycling, but without a long term vision and consistent strategy it is difficult to see how a significant change may be achieved. This paper presents three alternative visions for the role of walking and cycling in urban areas for the year 2030: each vision illustrates a ‘desirable’ walking- and cycling-oriented transport system against a different ‘exogenous social background’. These visions have been developed through a process of expert discussion and review and are intended to provide a stimulus for debate on the potential for and desirability of such alternative futures. Each is based on the UK and represents a substantial change to the current situation: in particular, each of the visions presents a view of a society where walking and cycling are considerably more important than is currently the case and where these modes cater for a much higher proportion of urban transport needs than at present. The visions show pictures of urban environments where dependence on motor vehicles has been reduced, in two of the visions to very low levels. The methodological approach for devising visions is informed by work on ‘utopian thinking’: a key concept underlying this approach is one of viewing the future in social constructivist terms (i.e. the future is what ‘we’, as a society, make it) rather than considering the future as something that can be ‘scientifically’ predicted by the extrapolation of current trends