16,446 research outputs found

    Diamond growth in premixed propylene-oxygen flames

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    Diamond film growth in low-pressure premixed propylene/oxygen flames is demonstrated. Well-faceted films are grown at a pressure of 180 Torr and a fuel/oxygen ratio of 0.47. Using propylene as the fuel may greatly improve the economics of flame synthesis of diamond, since propylene is an order of magnitude cheaper than acetylene

    Diamond films from combustion of methyl acetylene and propadiene

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    To date diamond films grown with the combustion technique have used either acetylene or, rarely, ethylene as the fuel. However, there are barriers to large scale commercialization of the combustion technique using either fuel. For example, acetylene is relatively expensive and difficult to handle, while the use of ethylene gives relatively low growth rates. In this letter we propose replacing acetylene with MAPPTM gas, a commercial mixture of methyl acetylene and propadiene in liquefied petroleum gas (primarily propylene). MAPP gas is considerably cheaper, safer, and easier to handle than acetylene. Furthermore, the experiments described here suggest that MAPP gas flames are only slightly less efficient than acetylene flames at converting fuel carbon atoms into diamond

    A People's History Of Recent Urban Transportation Innovation

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    Who are the people leading the charge in urban transportation? As our report explains, the short answer is that it takes leaders from three different sectors of urban society to make change happen quickly.First, there needs to be a robust civic vanguard, the more diverse their range of skills and participation, the better. Second, mayors, commissioners and other city leaders need to create the mandate and champion the change. The third sector is the agency staff. When these three sectors align, relatively quick transformation is possible. Several cities, including New York and Pittsburgh, recently experienced this alignment of a healthy civic community, a visionary and bold mayor and transportation head, and internal agency champions. Our report also highlighted the potential of other cities, such as Charlotte, where the civic sector continues to build on and widen their base

    Measuring producer welfare under output price uncertainty and risk non-neutrality

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    Procedures to measure the producer welfare effects of changes in an output price distribution under uncertainty are reviewed. Theory and numerical integration methods are combined to show how for any form of Marshallian risk-responsive supply, compensating variation of a change in higher moments of an output price distribution can be derived numerically. The numerical procedure enables measurement of producer welfare effects in the many circumstances in which risk and uncertainty are important elements. The practical ease and potential usefulness of the procedure is illustrated by measuring the producer welfare effects of USA rice policy.price uncertainty, risk non-neutrality, welfare economics, Demand and Price Analysis, Risk and Uncertainty,

    Application of graphics processing units to search pipelines for gravitational waves from coalescing binaries of compact objects

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    We report a novel application of a graphics processing unit (GPU) for the purpose of accelerating the search pipelines for gravitational waves from coalescing binaries of compact objects. A speed-up of 16-fold in total has been achieved with an NVIDIA GeForce 8800 Ultra GPU card compared with one core of a 2.5 GHz Intel Q9300 central processing unit (CPU). We show that substantial improvements are possible and discuss the reduction in CPU count required for the detection of inspiral sources afforded by the use of GPUs

    Test Set Diameter: Quantifying the Diversity of Sets of Test Cases

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    A common and natural intuition among software testers is that test cases need to differ if a software system is to be tested properly and its quality ensured. Consequently, much research has gone into formulating distance measures for how test cases, their inputs and/or their outputs differ. However, common to these proposals is that they are data type specific and/or calculate the diversity only between pairs of test inputs, traces or outputs. We propose a new metric to measure the diversity of sets of tests: the test set diameter (TSDm). It extends our earlier, pairwise test diversity metrics based on recent advances in information theory regarding the calculation of the normalized compression distance (NCD) for multisets. An advantage is that TSDm can be applied regardless of data type and on any test-related information, not only the test inputs. A downside is the increased computational time compared to competing approaches. Our experiments on four different systems show that the test set diameter can help select test sets with higher structural and fault coverage than random selection even when only applied to test inputs. This can enable early test design and selection, prior to even having a software system to test, and complement other types of test automation and analysis. We argue that this quantification of test set diversity creates a number of opportunities to better understand software quality and provides practical ways to increase it.Comment: In submissio

    2-Hydroxy-3-methoxybenzaldehyde (o-vanillin) revisited

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    The structure of ortho-vanillin, C[subscript 8]H[subscript 8]O[subscript 3], has been revisited with modern methods and at low temperature (100 K). The previous structure [Iwasaki et al. (1976). Acta Cryst. B32, 1264-1266] is confirmed, but geometric precision is improved by an order of magnitude. The C atom of the methoxy group lies close to the benzene ring plane, which is the most common geometry for -OMe groups lying ortho to -OH groups on an aromatic ring. The crystal structure displays one intramolecular O-H...O and three weak intermolecular C-H...O hydrogen bonds
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