548 research outputs found

    Spectral Characteristic Evolution: A New Algorithm for Gravitational Wave Propagation

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    We present a spectral algorithm for solving the full nonlinear vacuum Einstein field equations in the Bondi framework. Developed within the Spectral Einstein Code (SpEC), we demonstrate spectral characteristic evolution as a technical precursor to Cauchy Characteristic Extraction (CCE), a rigorous method for obtaining gauge-invariant gravitational waveforms from existing and future astrophysical simulations. We demonstrate the new algorithm's stability, convergence, and agreement with existing evolution methods. We explain how an innovative spectral approach enables a two orders of magnitude improvement in computational efficiency.Comment: 28 pages, 9 figure

    Spectral Cauchy Characteristic Extraction of strain, news and gravitational radiation flux

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    We present a new approach for the Cauchy-characteristic extraction of gravitational radiation strain, news function, and the flux of the energy-momentum, supermomentum and angular momentum associated with the Bondi-Metzner-Sachs asymptotic symmetries. In Cauchy-characteristic extraction, a characteristic evolution code takes numerical data on an inner worldtube supplied by a Cauchy evolution code, and propagates it outwards to obtain the space-time metric in a neighborhood of null infinity. The metric is first determined in a scrambled form in terms of coordinates determined by the Cauchy formalism. In prior treatments, the waveform is first extracted from this metric and then transformed into an asymptotic inertial coordinate system. This procedure provides the physically proper description of the waveform and the radiated energy but it does not generalize to determine the flux of angular momentum or supermomentum. Here we formulate and implement a new approach which transforms the full metric into an asymptotic inertial frame and provides a uniform treatment of all the radiation fluxes associated with the asymptotic symmetries. Computations are performed and calibrated using the Spectral Einstein Code (SpEC).Comment: 30 pages, 17 figure

    Uncertainty Quantification of Future Design Rainfall Depths in Korea

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    One of the most common ways to investigate changes in future rainfall extremes is to use future rainfall data simulated by climate models with climate change scenarios. However, the projected future design rainfall intensity varies greatly depending on which climate model is applied. In this study, future rainfall Intensity???Duration???Frequency (IDF) curves are projected using various combinations of climate models. Future Ensemble Average (FEA) is calculated using a total of 16 design rainfall intensity ensembles, and uncertainty of FEA is quantified using the coefficient of variation of ensembles. The FEA and its uncertainty vary widely depending on how the climate model combination is constructed, and the uncertainty of the FEA depends heavily on the inclusion of specific climate model combinations at each site. In other words, we found that unconditionally using many ensemble members did not help to reduce the uncertainty of future IDF curves. Finally, a method for constructing ensemble members that reduces the uncertainty of future IDF curves is proposed, which will contribute to minimizing confusion among policy makers in developing climate change adaptation policies

    An Economic Analysis of Bushfires Management Programs

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    Allocating scare resources for fire management strategies requires information on the extent of economic losses from bushfires and the efficiency of alternatives. Despite the severity of bushfires, there is no agreed approach in Australia for estimating economic losses from fires nor for evaluating the economic efficiency of alternative suppression strategies. The poster proposes approaches to assess the economic effects of bushfires on local and state economies and sets out models to evaluate the economic efficiency of two key bushfire management strategies: presuppression and suppression. The first model arises from questions concerning the value of pre-suppression (before the fire) fuel reduction activities, and the estimation of an economically optimal fire management budget. The fuel reduction burning aims to reduce losses from a major fire event. To determine how the budget should be allocated, a modification of the Cost plus Net Value Change model is being used. This model has the advantage that each of the influencing parameters is easy to adjust or even change for different areas in Australia. The second model allows straightforward comparisons of approaches to bushfire suppression, through a fire simulation model. The simulation allows comparisons of alternative strategies under similar fire conditions. The economic utility in suppression of fire engines, dozers and aircraft is evaluated using Cost Benefit Analysis and a Cost plus Loss framework. The paper presents useful tools for decision makers to make damage assessment from fire, resource allocation on pre-suppression and guidelines for operational decision making on suppression approaches.Resource /Energy Economics and Policy, A11, H4, Q51, Q54,

    Valuing adaptation under rapid change

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    AbstractThe methods used to plan adaptation to climate change have been heavily influenced by scientific narratives of gradual change and economic narratives of marginal adjustments to that change. An investigation of the theoretical aspects of how the climate changes suggests that scientific narratives of climate change are socially constructed, biasing scientific narratives to descriptions of gradual as opposed rapid, non-linear change. Evidence of widespread step changes in recent climate records and in model projections of future climate is being overlooked because of this. Step-wise climate change has the potential to produce rapid increases in extreme events that can cross institutional, geographical and sectoral domains.Likewise, orthodox economics is not well suited to the deep uncertainty faced under climate change, requiring a multi-faceted approach to adaptation. The presence of tangible and intangible values range across five adaptation clusters: goods; services; capital assets and infrastructure; social assets and infrastructure; and natural assets and infrastructure. Standard economic methods have difficulty in giving adequate weight to the different types of values across these clusters. They also do not account well for the inter-connectedness of impacts and subsequent responses between agents in the economy. As a result, many highly-valued aspects of human and environmental capital are being overlooked.Recent extreme events are already pressuring areas of public policy, and national strategies for emergency response and disaster risk reduction are being developed as a consequence. However, the potential for an escalation of total damage costs due to rapid change requires a coordinated approach at the institutional level, involving all levels of government, the private sector and civil society.One of the largest risks of maladaptation is the potential for un-owned risks, as risks propagate across domains and responsibility for their management is poorly allocated between public and private interests, and between the roles of the individual and civil society. Economic strategies developed by the disaster community for disaster response and risk reduction provide a base to work from, but many gaps remain.We have developed a framework for valuing adaptation that has the following aspects: the valuation of impacts thus estimating values at risk, the evaluation of different adaptation options and strategies based on cost, and the valuation of benefits expressed as a combination of the benefits of avoided damages and a range of institutional values such as equity, justice, sustainability and profit.The choice of economic methods and tools used to assess adaptation depends largely on the ability to constrain uncertainty around problems (predictive uncertainty) and solutions (outcome uncertainty). Orthodox methods can be used where both are constrained, portfolio methodologies where problems are constrained and robust methodologies where solutions are constrained. Where both are unconstrained, process-based methods utilising innovation methods and adaptive management are most suitable. All methods should involve stakeholders where possible.Innovative processes methods that enable transformation will be required in some circumstances, to allow institutions, sectors and communities to prepare for anticipated major change.Please cite this report as: Jones, RN, Young, CK, Handmer, J, Keating, A, Mekala, GD, Sheehan, P 2013 Valuing adaptation under rapid change, National Climate Change Adaptation Research Facility, Gold Coast, pp. 192.The methods used to plan adaptation to climate change have been heavily influenced by scientific narratives of gradual change and economic narratives of marginal adjustments to that change. An investigation of the theoretical aspects of how the climate changes suggests that scientific narratives of climate change are socially constructed, biasing scientific narratives to descriptions of gradual as opposed rapid, non-linear change. Evidence of widespread step changes in recent climate records and in model projections of future climate is being overlooked because of this. Step-wise climate change has the potential to produce rapid increases in extreme events that can cross institutional, geographical and sectoral domains.Likewise, orthodox economics is not well suited to the deep uncertainty faced under climate change, requiring a multi-faceted approach to adaptation. The presence of tangible and intangible values range across five adaptation clusters: goods; services; capital assets and infrastructure; social assets and infrastructure; and natural assets and infrastructure. Standard economic methods have difficulty in giving adequate weight to the different types of values across these clusters. They also do not account well for the inter-connectedness of impacts and subsequent responses between agents in the economy. As a result, many highly-valued aspects of human and environmental capital are being overlooked.Recent extreme events are already pressuring areas of public policy, and national strategies for emergency response and disaster risk reduction are being developed as a consequence. However, the potential for an escalation of total damage costs due to rapid change requires a coordinated approach at the institutional level, involving all levels of government, the private sector and civil society.One of the largest risks of maladaptation is the potential for un-owned risks, as risks propagate across domains and responsibility for their management is poorly allocated between public and private interests, and between the roles of the individual and civil society. Economic strategies developed by the disaster community for disaster response and risk reduction provide a base to work from, but many gaps remain.We have developed a framework for valuing adaptation that has the following aspects: the valuation of impacts thus estimating values at risk, the evaluation of different adaptation options and strategies based on cost, and the valuation of benefits expressed as a combination of the benefits of avoided damages and a range of institutional values such as equity, justice, sustainability and profit.The choice of economic methods and tools used to assess adaptation depends largely on the ability to constrain uncertainty around problems (predictive uncertainty) and solutions (outcome uncertainty). Orthodox methods can be used where both are constrained, portfolio methodologies where problems are constrained and robust methodologies where solutions are constrained. Where both are unconstrained, process-based methods utilising innovation methods and adaptive management are most suitable. All methods should involve stakeholders where possible.Innovative processes methods that enable transformation will be required in some circumstances, to allow institutions, sectors and communities to prepare for anticipated major change

    Selecting content for an introductory training course in industrial relations

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    A nine-member panel with acknowledged expertise across a broad range of industrial relations interests made up the respondent population. Panelists opinions were collected, summarised, then re-submitted to the panel with an invitation to review their opinions in the light of the group summary. This process was repeated three times -the first consisting of individual progressively structured interviews, the other two being written surveys. A high level of consensus was achieved, both in ;1 content selections and in the reasons for choosing such topics. This resulted in the development of a course outline consisting of the following major topics - historical overview, overview of the formal industrial relations system, role of trade unions and employers, industrial relations in the workplace and communications. Sub-content for each heading was also identified and included in the resulting outline, with justification in the form of reasons for those selections. The course outline offers a guide to content suitable for inclusion in a short (two to three day) introductory training course to the Western Australian industrial relations system. It is directed towards the needs of key employer and employee representatives in the workplace who, whilst not industrial relations specialists, nonetheless have a role in workplace decision making. The focus of the course is upon providing information which is fundamental to an understanding of industrial relations at both the formal and workplace levels. The reasons given for selection show the validity and relevance of this content for workplace participants. As such the course is capable of adaptation to a wide range of individual learning and industry needs

    Making a success of ‘failure’: a Science Studies analysis of PILOT and SERC in the context of Australian space science

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    This thesis presents an in-depth empirical investigation, based on participant observation, interviews and publicly available materials, of PILOT and SERC, two recent Australian space science projects that were both connected to the problem of space debris. While PILOT’s proposal for funding failed, SERC was successfully funded yet failed to reach its initially stated goal of demonstrating the possibility of Active Debris Removal (ADR) using a ground-based high power laser combined with laser guide star adaptive optics. My analysis illustrates that the Australian space science funding and policy environment changed significantly in the brief period between PILOT’s unsuccessful proposal and SERC’s formation, marking the period of time in which dual-use space capability development was recognised as a political strategic priority. In SERC’s case, dual-use technology has been developed through (substantially) publicly funded institutions and by civil scientists. I argue that the current arrangement of policy and funding structures in the Australian space sciences sector facilitates engagement in dual-use technology development in such a way that two outcomes emerge: first, that moral responsibility for the products of such research is institutionally and individually avoided by distributing it ‘up the chain’ to national governmental entities, and second, that international legal responsibility is likewise avoided at a national level by distributing it ‘down the chain’ to institutions. I demonstrate how policy and funding conditions in Australia allowed individuals working in, and adjacent to, the space sciences to maintain, unchallenged, the convenient fiction that science is itself amoral and, to some extent, apolitical
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