Nonlinear Attitude Filtering: A Comparison Study

This paper contains a concise comparison of a number of nonlinear attitude filtering methods that have attracted attention in the robotics and aviation literature. With the help of previously published surveys and comparison studies, the vast literature on the subject is narrowed down to a small pool of competitive attitude filters. Amongst these filters is a second-order optimal minimum-energy filter recently proposed by the authors. Easily comparable discretized unit quaternion implementations of the selected filters are provided. We conduct a simulation study and compare the transient behaviour and asymptotic convergence of these filters in two scenarios with different initialization and measurement errors inspired by applications in unmanned aerial robotics and space flight. The second-order optimal minimum-energy filter is shown to have the best performance of all filters, including the industry standard multiplicative extended Kalman filter (MEKF)

Epistemic geographies of climate change: the IPCC and the spaces, boundaries and politics of knowing

Science, like other realms of human activity, has its geographies. It proceeds in and through space, and participates in the construction of the political and cultural geographies by which human interactions with the nonhuman come to be known, understood and governed. The phenomenon of climate change stands at this juncture of science, politics, and the elemental materiality of the nonhuman. High-profile controversies about the physical reality, effects and management of the changing climate point to more deep-seated contestations about the place of science in modern democratic societies. This thesis engages with literatures on the historical and cultural geographies of science in order to open-up questions about the situatedness of climate change knowledges, the contested boundaries between the scientific and the political, and the spatial politics of relating epistemic claims to normative interventions in the world. The thesis proceeds through a series of linked case studies which traverse a range of emergent transnational spaces of knowledge production. It begins inside the Intergovernmental Panel on Climate Change (IPCC) and moves through the contested spaces of international climate diplomacy at the 2009 Copenhagen climate talks and through diverse cultures of knowledge authorisation in Indian climate politics. The thesis develops the notions of ‘boundary spaces’ and ‘epistemic geographies’ to capture the emergence, conjuncture and contestation of different modes of knowing and governing climate change. By following the objects of climate change knowledges – like visualisations, numerical targets, simulation models and predictions – conceptual distinctions between the spaces of knowledge production and consumption break down. Instead, a picture emerges of travelling knowledges which emphasises mutability, interpretive flexibility, and the spatial and discursive co-production of the epistemic and the normative. It is argued that by moving from ‘geographies of science’ to ‘epistemic geographies’, the hybridity of science and politics can be more effectively written-in to our accounts of contemporary knowledge politics

What triggers a radio AGN? The intriguing case of PKSB 1718-649

We present new Australia Telescope Compact Array (ATCA) observations of the young (< 10^2 years) radio galaxy PKS B1718-649. We study the morphology and the kinematics of the neutral hydrogen (HI) disk (M(HI) = 1.1x 10^10 M(sun), radius ~ 30 kpc). In particular, we focus on the analysis of the cold gas in relation to the triggering of the nuclear activity. The asymmetries at the edges of the disk date the last interaction with a companion to more than 1 Gyr ago. The tilted-ring model of the HI disk shows that this event may have formed the disk as we see it now, but that it may have not been responsible for triggering the AGN. The long timescales of the interaction are incompatible with the short ones of the radio activity. In absorption, we identify two clouds with radial motions which may represent a population that could be involved in the triggering of the radio activity. We argue that PKS B1718-649 may belong to a family of young low-excitation radio AGN where, rather than through a gas rich merger, the active nuclei (AGN) are triggered by local mechanisms such as accretion of small gas clouds.Comment: 8 pages, 9 figures, Accepted to A&

Science advice for global challenges: learning from trade-offs in the IPCC

In the context of ongoing debates about the place of knowledge and expertise in the governance of global challenges, this article seeks to promote cross-sectoral learning about the politics and pitfalls of global science advice. It begins with the intertwined histories of the Intergovernmental Panel on Climate Change (IPCC) and the global climate policy regime, before examining the politics of different ‘framings’ of the climate problem and the challenges of building and communicating scientific consensus. We then identify three important trade-offs which the IPCC has had to negotiate: global versus local; scientific disinterestedness versus policy-relevance; and consensus versus plurality. These lessons are especially timely as global institutions begin to convene knowledge to address urgent sustainable development challenges posed by anti-microbial resistance (AMR). While the IPCC experience does not provide a wholly transportable model for science advice, we show why similar trade-offs need to be addressed at an early stage by architects of advisory systems for AMR as well as other global challenges

A Catalogue of Digital Editions

Since the earliest days of hypertext, textual scholars have produced, discussed and theorised upon critical digital editions of manuscripts, in order to investigate how digital technologies can provide another means to present and enable the interpretative study of text. This work has generally been done by looking at particular case studies or examples of critical digital editions, and, as a result, there is no overarching understanding of how digital technologies have been employed across the full range of textual interpretations. This chapter will describe the creation of a catalogue of digital editions that could collect information about extant digital editions and, in so doing, contribute to research in related disciplines. The resulting catalogue will provide a means of answering, in the form of a quantitative survey, the following research questions: What makes a good digital edition? What features do digital editions share? What is the state of the art in the field of digital editions? Why are there so few electronic editions of ancient texts, and so many of texts from other periods? By collecting data regarding existing digital editions, and corresponding directly with the projects in question, we provide a unique record of extant digital critical editions of text across a range of subject areas, and show how this collaboratively edited catalogue can benefit the Digital Humanities community