103,563 research outputs found

    Low-cost, portable fire hose tester

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    Availability of pumping unit permits scheduling and performing required periodic hose tests in proper manner while retaining full fire equipment readiness. Use of pumping unit preserves operating life and capability of pumper truck

    A generalized correlation of experimental flat-plate collector performance

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    A generalized collector performance correlation was derived and shown by experimental verification to be of the proper form to account for the majority of the variable conditions encountered both in outdoor and in indoor collector tests. This correlation permits a determination of collector parameters which are essentially nonvarying under conditions which do vary randomly (outdoors) or conditions which vary in a controlled manner (indoors - simulator). It was shown that correlation of the experimental performance of collectors allows the following: (1) comparisons of different collector designs; (2) collector performance prediction under conditions that differ from the conditions of the test program; and (3) monitoring performance degradation effects

    Application of thermal radiation data to fishery oceanography

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    Work on Project Little Window-1 and -2, DRIR data conversion, improvements on the APT receiver, equatorial upwelling, and the topic of thermal fronts is discussed

    Structure and finiteness properties of subdirect products of groups

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    We investigate the structure of subdirect products of groups, particularly their finiteness properties. We pay special attention to the subdirect products of free groups, surface groups and HNN extensions. We prove that a finitely presented subdirect product of free and surface groups virtually contains a term of the lower central series of the direct product or else fails to intersect one of the direct summands. This leads to a characterization of the finitely presented subgroups of the direct product of 3 free or surface groups, and to a solution to the conjugacy problem for arbitrary finitely presented subgroups of direct products of surface groups. We obtain a formula for the first homology of a subdirect product of two free groups and use it to show there is no algorithm to determine the first homology of a finitely generated subgroup.Comment: 29 pages, no figure

    Formulation and evaluation of C-Ether fluids as lubricants useful to 260 C

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    Three base stocks were evaluated in bench and bearing tests to determine their suitability for use at bulk oil temperatures (BOT) from -40 C to +260 C. A polyol ester gave good bearing tests at a bulk temperature of 218 C, but only a partially successful run at 274 C. These results bracket the fluid's maximum operating temperature between these values. An extensive screening program selected lubrication additives for a C-ether (modified polyphenyl ether) base stock. One formulation lubricated a bearing for 111 hours at 274 C (BOT), but this fluid gave many deposit related problems. Other C-ether blends produced cage wear or fatigue failures. Studies of a third fluid, a C-ether/disiloxane blend, consisted of bench oxidation and lubrication tests. These showed that some additives react differently in the blend than in pure C-ethers

    Thermodynamics and kinetics of the sulfation of porous calcium silicate

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    The sulfation of plasma sprayed calcium silicate in flowing SO2/air mixtures at 900 and 1000 C was investigated thermogravimetrically. Reaction products were analyzed using electron microprobe and X-ray diffraction analysis techniques, and results were compared with thermodynamic predictions. The percentage, by volume, of SO2 in air was varied between 0.036 and 10 percent. At 10 percent SO2 the weight gain curve displays a concave downward shoulder early in the sulfation process. An analytical model was developed which treats the initial process as one which decays exponentially with increasing time and the subsequent process as one which decays exponentially with increasing weight gain. At lower SO2 levels the initial rate is controlled by the reactant flow rate. At 1100 C and 0.036 percent SO2 there is no reaction, in agreement with thermodynamic predictions

    Galactic oscillations

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    Several oscillations have been identified in spherical galaxy models. These are normal mode oscillations in a stable galaxy. Each has its own distinct period and spatial form, and each rings without detectable damping through a Hubble time. The most important are: (1) a simple radial pulsation (fundamental mode), in which all parts of the galaxy move inward or outward with the same phase; and (2) a second spherically symmetrical radial mode with one node, so material inside the node moves outward when material outside moves inward. Numerical experiments suggest that normal mode oscillations may be present in nearly all galaxies at a considerably higher amplitude than has previously been thought. Amplitudes typically run a few percent of equilibrium values, and periods are around 50-300 Myrs in typical galaxies. These time scales are long enough that gas trapped near the center could cool during an oscillation cycle, allowing star formation activity. The second mode oscillations could cause bursts of star formation

    Coherency in space of lake and river temperature and water quality records

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    Environmental time series observed over 100’s of monitoring locations usually possess some spatial structure in terms of common patterns throughout time, commonly described as temporal coherence. This paper will apply, develop and compare two methods for clustering time series on the basis of their patterns over time. The first approach treats the time series as functional data and applies hierarchical clustering while the second uses a state-space model based clustering approach. Both methods are developed to incorporate spatial correlation and stopping criteria are investigated to identify an appropriate number of clusters. The methods are applied to Total Organic Carbon data from river sites across Scotland

    Computer programs for the interpretation of low resolution mass spectra: Program for calculation of molecular isotopic distribution and program for assignment of molecular formulas

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    Two FORTRAN computer programs for the interpretation of low resolution mass spectra were prepared and tested. One is for the calculation of the molecular isotopic distribution of any species from stored elemental distributions. The program requires only the input of the molecular formula and was designed for compatability with any computer system. The other program is for the determination of all possible combinations of atoms (and radicals) which may form an ion having a particular integer mass. It also uses a simplified input scheme and was designed for compatability with any system

    Study on joint thermal conductance in vacuum Final report

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    Bright leveling copper plating for improvement of thermal conductance in mechanical joints in vacuu
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