3,606 research outputs found

    Emissions and Total Energy Consumption of a Multicylinder Piston Engine Running on Gasoline and a Hydrogen-gasoline Mixture

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    A multicylinder reciprocating engine was used to extend the efficient lean operating range of gasoline by adding hydrogen. Both bottled hydrogen and hydrogen produced by a research methanol steam reformer were used. These results were compared with results for all gasoline. A high-compression-ratio, displacement production engine was used. Apparent flame speed was used to describe the differences in emissions and performance. Therefore, engine emissions and performance, including apparent flame speed and energy lost to the cooling system and the exhaust gas, were measured over a range of equivalence ratios for each fuel. All emission levels decreased at the leaner conditions. Adding hydrogen significantly increased flame speed over all equivalence ratios

    Galois Theory of Parameterized Differential Equations and Linear Differential Algebraic Groups

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    We present a Galois theory of parameterized linear differential equations where the Galois groups are linear differential algebraic groups, that is, groups of matrices whose entries are functions of the parameters and satisfy a set of differential equations with respect to these parameters. We present the basic constructions and results, give examples, discuss how isomonodromic families fit into this theory and show how results from the theory of linear differential algebraic groups may be used to classify systems of second order linear differential equations

    Measurement of surface roughness slope

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    Instrument, consisting of isolator, differentiator, absolute value circuit, and integrator, uses output signal from surface texture analyzer profile-amplifier to calculate surface roughness slope. Calculations provide accurate, instantaneous value of the slope. Instrument is inexpensive and applicable to any commerical surface texture analyzer

    Tannakian approach to linear differential algebraic groups

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    Tannaka's Theorem states that a linear algebraic group G is determined by the category of finite dimensional G-modules and the forgetful functor. We extend this result to linear differential algebraic groups by introducing a category corresponding to their representations and show how this category determines such a group.Comment: 31 pages; corrected misprint

    The Mercury-Redstone project

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    Mercury-Redstone project development history, and contributions to future manned spacecraft design and operatio

    Dietary flavonoid intakes and CVD incidence in the Framingham Offspring Cohort

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    This study examines the relationship between long-term intake of six flavonoid classes and incidence of CVD and CHD, using a comprehensive flavonoid database and repeated measures of intake, while accounting for possible confounding by components of a healthy dietary pattern. Flavonoid intakes were assessed using a FFQ among the Framingham Offspring Cohort at baseline and three times during follow-up. Cox proportional hazards regression was used to characterise prospective associations between the natural logarithms of flavonoid intakes and CVD incidence using a time-dependent approach, in which intake data were updated at each examination to represent average intakes from previous examinations. Mean baseline age was 54 years, and 45 % of the population was male. Over an average 14·9 years of follow-up among 2880 participants, there were 518 CVD events and 261 CHD events. After multivariable adjustment, only flavonol intake was significantly associated with lower risk of CVD incidence (hazard ratios (HR) per 2·5-fold flavonol increase = 0·86, Ptrend = 0·05). Additional adjustment for total fruit and vegetable intake and overall diet quality attenuated this observation (HR = 0·89, Ptrend = 0·20 and HR = 0·92, Ptrend = 0·33, respectively). There were no significant associations between flavonoids and CHD incidence after multivariable adjustment. Our findings suggest that the observed association between flavonol intake and CVD risk may be a consequence of better overall diet. However, the strength of this non-significant association was also consistent with relative risks observed in previous meta-analyses, and therefore a modest benefit of flavonol intake on CVD risk cannot be ruled out

    Accurate surface temperature measurements at liquid helium conditions in space environment facilities

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    Germanium resistance thermometer, lead wire heat sink, and high thermal conducting epoxy fastening techniques to measure wall temperature in cryogenically cooled space simulator

    Canada’s Earthquakes: ‘The Good, the Bad, and the Ugly’

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    Much of Canada is ‘earthquake country’. Tiny earthquakes (that can only be recorded by seismographs) happen every day. On average, earthquakes large enough to be felt occur every week in Canada, damaging earthquakes are years to decades apart, and some of the world’s largest earthquakes are typically separated by intervals of centuries. In this article, we provide details on the most significant earthquakes that have been recorded in, or near, Canada, including where and when they occurred, how they were felt, and the effects of those earthquakes. We also provide a brief review of how earthquakes are monitored across Canada and some recent earthquake hazard research. It is the results of this monitoring and research, which provide knowledge on earthquake hazard, that are incorporated into the National Building Code of Canada. This, in turn, will contribute to reduced property losses from future earthquakes across Canada. SOMMAIRE Un bonne partie du Canada est un ‘pays de séismes’. De petits séismes (que seuls les séismographes peuvent enregistrer) s’y produisent quotidiennement. En moyenne, un séisme assez fort pour qu’on le ressente s’y produit à intervalle d’une semaine; assez fort pour causer des dommages s’y produit à intervalle de quelques années à quelques décennies; alors que l’intervalle de récurrence des plus grands séismes est de l’ordre des siècles. Dans le présent article on trouvera des détails sur les plus importants séismes s’étant produits sur ou à proximité du territoire canadien, incluant le lieu et le moment, leurs manifestations et leurs répercussions. On y décrit sommairement les moyens de détection déployés sur le territoire canadien ainsi que quelques-unes des recherches récentes sur les risques sismiques. Ce sont les résultats des efforts de surveillance et des recherches sur les tremblements de terre qui ont été intégrés dans le Code national du bâtiment du Canada. Et cela aidera à amoindrir les répercussions des séismes à venir sur la propriété
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