11,531 research outputs found

    Memory and Film

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    The Financial Accounting Standards Board of Derivatives Activity and Disclosure

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    Autonomous Guidance Algorithms for NASA Learn-to-Fly Technology Development

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    Learn-to-Fly (L2F) is an advanced technology development effort under the NASA Transformative Aeronautics Concepts Program (TACP) that is aimed at assessing the feasibility of self-learning flight vehicles. Specifically, research has been conducted to demonstrate the potential to merge two enabling technologies; real-time aerodynamic modeling and adaptive controls, to substantially reduce the typical ground and flight testing requirements for air vehicle design. The approach to this effort involved development of unique airframes and on-board algorithms to demonstrate key L2F technologies on a fully autonomous flight test vehicle. This research, that included an aggressive flight test program, was intended to rapidly advance these technologies and demonstrate capabilities of the L2F approach. Key components of the L2F architecture include real-time aerodynamic modeling, adaptive controls and control allocation, and guidance. This paper provides an overview of the guidance algorithm which primarily served as an executive function to coordinate control commands for range navigation and the desired test conditions, provide autonomous envelope limiting/expansion and enable automatic landing to touchdown with no intervention from a human operator. A discussion of the L2F concept-of-operations and unique flight testing considerations, which influenced the guidance functional requirements, is included and results of recent flight testing are presented

    A micro-meso-macro perspective on the methodology of evolutionary economics: integrating history, simulation and econometrics

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    Applied economics has long been dominated by multiple regression techniques. In this regard, econometrics has tended to have a narrower focus than, for example, psychometrics in psychology. Over the last two decades, the simulation and calibration approach to modeling has become more popular as an alternative to traditional econometric strategies. However, in contrast to the well-developed methodologies that now exist in econometrics, simulation/calibration remains exploratory and provisional, both as an explanatory and as a predictive modelling technique although clear progress has recently been made in this regard (see Brenner and Werker (2006)). In this paper, we suggest an approach that can usefully integrate both of these modelling strategies into a coherent evolutionary economic methodology.

    INTERREGIONAL COMPETITIVE IMPACT OF URBAN INFLUENCED FARMLAND PRICES

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    The paper's hypothesis is that the farmers using land with urban influenced prices are at a competitive disadvantage because their land input cost exceeds its calitialized earning power while land prices for other farmers are based on earning ability. This hypothesis was investigated by comparing rates of return to land in Massachusetts and two non-urban dairy regions in Wisconsin. Both areas have low rates of return compared to contemporary market interest rates with Massachusetts rates somewhat below those in Wisconsin. When additional factors are considered, the hypothesis is weakly supported, at best.Land Economics/Use,

    From Simplistic to Complex Systems in Economics

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    The applicability of complex systems theory in economics is evaluated and compared with standard approaches to economic theorizing based upon constrained optimization. A complex system is defined in the economic context and differentiated from complex systems in physio-chemical and biological settings. It is explained why it is necessary to approach economic analysis from a network, rather than a production and utility function perspective, when we are dealing with complex systems. It is argued that much of heterodox thought, particularly in neo-Schumpeterian and neo-Austrian evolutionary economics, can be placed within a complex systems perspective upon the economy. The challenge is to replace prevailing 'simplistic' theories, based in constrained optimization, with 'simple' theories, derived from network representations in which value is created through the establishment of new connections between elements.

    On the stability of the generalized, finite deformation correspondence model of peridynamics

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    A class of peridynamic material models known as constitutive correspondence models provide a bridge between classical continuum mechanics and peridynamics. These models are useful because they allow well-established local constitutive theories to be used within the nonlocal framework of peridynamics. A recent finite deformation correspondence theory (Foster and Xu, 2018) was developed and reported to improve stability properties of the original correspondence model (Silling et al., 2007). This paper presents a stability analysis that indicates the reported advantages of the new theory were overestimated. Homogeneous deformations are analyzed and shown to exibit unstable material behavior at the continuum level. Additionally, the effects of a particle discretization on the stability of the model are reported. Numerical examples demonstrate the large errors induced by the unstable behavior. Stabilization strategies and practical applications of the new finite deformation model are discussed

    Is There an Optimal Entry Time for Carbon Capture and Storage? A Case Study for Australia's National Electricity Market

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    This paper examines the economic competitiveness of implementing Carbon Capture and Storage (CCS) for deployment on the Australia’s National Electricity Market (NEM) against conventional base load electricity generation. By examining the Levelised Cost of Energy (LCOE) for sent out generation as a suitable hurdle for judging the future prospects of different technology types, we examine the likely mix of generation assets that could be invested in. After examining the LCOE it is shown that CCS enabled technologies will not be competitive in Australia until 2025, which is well beyond the first emissions reduction target for 2020.Levelised Cost of Energy; Electricity Generation; Emissions Reduction; Carbon Capture and Storage
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