106 research outputs found
Intelligent Cooperative Control Architecture: A Framework for Performance Improvement Using Safe Learning
Planning for multi-agent systems such as task assignment for teams of limited-fuel unmanned aerial vehicles (UAVs) is challenging due to uncertainties in the assumed models and the very large size of the planning space. Researchers have developed fast cooperative planners based on simple models (e.g., linear and deterministic dynamics), yet inaccuracies in assumed models will impact the resulting performance. Learning techniques are capable of adapting the model and providing better policies asymptotically compared to cooperative planners, yet they often violate the safety conditions of the system due to their exploratory nature. Moreover they frequently require an impractically large number of interactions to perform well. This paper introduces the intelligent Cooperative Control Architecture (iCCA) as a framework for combining cooperative planners and reinforcement learning techniques. iCCA improves the policy of the cooperative planner, while reduces the risk and sample complexity of the learner. Empirical results in gridworld and task assignment for fuel-limited UAV domains with problem sizes up to 9 billion state-action pairs verify the advantage of iCCA over pure learning and planning strategies
Crowdsourced Mapping in Crisis Zones: Collaboration, Organisation and Impact
Crowdsourced mapping has become an integral part of humanitarian response, with high profile deployments of platforms following the Haiti and Nepal earthquakes, and the multiple projects initiated during the Ebola outbreak in North West Africa in 2014, being prominent examples. There have also been hundreds of deployments of crowdsourced mapping projects across the globe, that did not have a high profile. This paper, through an analysis of 51 mapping deployments between 2010–2016, complimented with expert interviews, seeks to explore the organisational structures that create the conditions for effective mapping actions, and the relationship between the commissioning body, often a Non-Governmental Organisation (NGO) and the volunteers who regularly make up the team charged with producing the map. The research suggests that there are three distinct areas that need to be improved in-order to provide appropriate assistance through mapping in humanitarian crisis; regionalise; prepare; and research. The paper concludes, based on the case studies, how each of these areas can be handled more effectively, concluding that failure to implement one area sufficiently can lead to overall project failure
Neuroevolutionary reinforcement learning for generalized control of simulated helicopters
This article presents an extended case study in the application of neuroevolution to generalized simulated helicopter hovering, an important challenge problem for reinforcement learning. While neuroevolution is well suited to coping with the domain’s complex transition dynamics and high-dimensional state and action spaces, the need to explore efficiently and learn on-line poses unusual challenges. We propose and evaluate several methods for three increasingly challenging variations of the task, including the method that won first place in the 2008 Reinforcement Learning Competition. The results demonstrate that (1) neuroevolution can be effective for complex on-line reinforcement learning tasks such as generalized helicopter hovering, (2) neuroevolution excels at finding effective helicopter hovering policies but not at learning helicopter models, (3) due to the difficulty of learning reliable models, model-based approaches to helicopter hovering are feasible only when domain expertise is available to aid the design of a suitable model representation and (4) recent advances in efficient resampling can enable neuroevolution to tackle more aggressively generalized reinforcement learning tasks
Measurement of the Branching Ratio
Experiment E949 at Brookhaven National Laboratory studied the rare decay
\ and other processes with an exposure of 's. The data were analyzed using a blind analysis technique
yielding one candidate event with an estimated background of
events. Combining this result with the observation of two candidate events by
the predecessor experiment E787 gave the branching ratio
{\calB}(K^+\to\pi^+\nu\bar{\nu})=(1.47^{+1.30}_{-0.89})\times 10^{-10},
consistent with the Standard Model prediction of . This is a more detailed report of results previously published in
Physical Review Letters.Comment: 99 pages, 32 figures, 12 tables. Added authors, corrected typos and
modify the text suggested by the referees. Accepted for publication in PR
F-Spondin/spon1b Expression Patterns in Developing and Adult Zebrafish
F-spondin, an extracellular matrix protein, is an important player in embryonic morphogenesis and CNS development, but its presence and role later in life remains largely unknown. We generated a transgenic zebrafish in which GFP is expressed under the control of the F-spondin (spon1b) promoter, and used it in combination with complementary techniques to undertake a detailed characterization of the expression patterns of F-spondin in developing and adult brain and periphery. We found that F-spondin is often associated with structures forming long neuronal tracts, including retinal ganglion cells, the olfactory bulb, the habenula, and the nucleus of the medial longitudinal fasciculus (nMLF). F-spondin expression coincides with zones of adult neurogenesis and is abundant in CSF-contacting secretory neurons, especially those in the hypothalamus. Use of this new transgenic model also revealed F-spondin expression patterns in the peripheral CNS, notably in enteric neurons, and in peripheral tissues involved in active patterning or proliferation in adults, including the endoskeleton of zebrafish fins and the continuously regenerating pharyngeal teeth. Moreover, patterning of the regenerating caudal fin following fin amputation in adult zebrafish was associated with F-spondin expression in the blastema, a proliferative region critical for tissue reconstitution. Together, these findings suggest major roles for F-spondin in the CNS and periphery of the developing and adult vertebrate
Critical factors in the empirical performance of temporal difference and evolutionary methods for reinforcement learning
Libertarian paternalism: Policy and everyday translations of the rational and the affective
Following the financial collapse in 2008 many commentators went onto pronounce the end of neoliberalism as a credible system for managing welfare state capitalism. The narrow economic belief in individuals as rational utility maximizers (the linchpin of neoliberal governance) was proved to be uncomfortably inaccurate. In light of these claims, British governments and think tanks have published various research and pol-icy documents promoting the use of soft forms of state power to ‘nudge’ citizens into behaving responsibly and rationally. Through an analysis of key policy documents and academic texts, I examine the repertoires and formulations informing this emerging governmental rationality (‘libertarian paternalism’) and draw together these perspectives to explore their effects in terms of framing policy understandings of the rational and the emotional. I conclude the article by utilizing a discursive psychology approach with the aim to problematize existing policy (mis)understandings of emotion as automated and unreflexive
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