3,188 research outputs found

    How to find real-world applications for compressive sensing

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    The potential of compressive sensing (CS) has spurred great interest in the research community and is a fast growing area of research. However, research translating CS theory into practical hardware and demonstrating clear and significant benefits with this hardware over current, conventional imaging techniques has been limited. This article helps researchers to find those niche applications where the CS approach provides substantial gain over conventional approaches by articulating lessons learned in finding one such application; sea skimming missile detection. As a proof of concept, it is demonstrated that a simplified CS missile detection architecture and algorithm provides comparable results to the conventional imaging approach but using a smaller FPA. The primary message is that all of the excitement surrounding CS is necessary and appropriate for encouraging our creativity but we all must also take off our "rose colored glasses" and critically judge our ideas, methods and results relative to conventional imaging approaches.Comment: 10 page

    Growth or decline in the Church of England during the decade of Evangelism: did the Churchmanship of the Bishop matter?

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    The Decade of Evangelism occupied the attention of the Church of England throughout the 1990s. The present study employs the statistics routinely published by the Church of England in order to assess two matters: the extent to which these statistics suggest that the 43 individual dioceses finished the decade in a stronger or weaker position than they had entered it and the extent to which, according to these statistics, the performance of dioceses led by bishops shaped in the Evangelical tradition differed from the performance of dioceses led by bishops shaped in the Catholic tradition. The data demonstrated that the majority of dioceses were performing less effectively at the end of the decade than at the beginning, in terms of a range of membership statistics, and that the rate of decline varied considerably from one diocese to another. The only exception to the trend was provided by the diocese of London, which experienced some growth. The data also demonstrated that little depended on the churchmanship of the diocesan bishop in shaping diocesan outcomes on the performance indicators employed in the study

    Conservation laws for potential vorticity in a salty ocean or cloudy atmosphere

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    One of the most important conservation laws in atmospheric and oceanic science is conservation of potential vorticity. The original derivation is approximately a century old, in the work of Rossby and Ertel, and it is related to the celebrated circulation theorems of Kelvin and Bjerknes. However, the laws apply to idealized fluids, and extensions to more realistic scenarios have been problematic. Here, these laws are extended to hold with additional fundamental complexities, including salinity in the ocean, or moisture and clouds in the atmosphere. In the absence of these additional complexities, it is known that potential vorticity is conserved following each fluid parcel; here, for a salty ocean or cloudy atmosphere, the general conserved quantity is potential vorticity integrated over certain pancake-shaped volumes. Furthermore, the conservation laws are also related to a symmetry in the Lagrangian, which brings a connection to the symmetry-conservation relationships seen in other areas of physics.Comment: 11 pages, 3 figure

    The Deepwater Horizon Oil Spill And Gulf Of Mexico Shelf Hypoxia

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    The oil/water/dispersant mixture from the 2010 Deepwater Horizon oil spill was juxtaposed on the Louisiana continental shelf with the annual development of oxygen-depleted bottom waters. There was uncertainty whether the oil from the spill might worsen the extent or severity of the seasonal hypoxic area formation in 2010. The surface and bottom water hydrocarbons in May were elevated compared to in June and July, while the bottom-water dissolved oxygen concentrations were higher in May and June compared to in July. The degradation of oil in the water column or sediments was not known. The results of an empirical orthogonal functions (EOF) analysis of the progression of hypoxia development in May, June and July 2010, and an analysis of conditions in July compared to a 27-year background database, indicated no difference in oxygen concentrations for May, June or July 2010, with or without oil data included, nor any difference in July 2010 compared to other years. The analysis instead indicated that, in all years compared, the hypoxic area increased with higher river discharge, higher nitrate-N load, an easterly (westward) wind and reduced wind speed. Although the analyses did not demonstrate that the oil spill affected, or did not affect, the size of the 2010 hypoxic zone, there was evidence that the 2010 hypoxia season did not differ from the long-term record
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