We describe a directed search for continuous gravitational waves in data from the sixth initial LIGO science run. The target was the nearby globular cluster NGC 6544 at a distance of ≈2.7 kpc. The search * Deceased.
SEARCH FOR CONTINUOUS GRAVITATIONAL WAVES …PHYSICAL REVIEW D 95, 082005 (2017) 082005-5 covered a broad band of frequencies along with first and second frequency derivatives for a fixed sky position. The search coherently integrated data from the two LIGO interferometers over a time span of 9.2 days using the matched-filtering F -statistic. We found no gravitational-wave signals and set 95% confidence upper limits as stringent as 6.0 × 10 −25 on intrinsic strain and 8.5 × 10 −6 on fiducial ellipticity. These values beat the indirect limits from energy conservation for stars with characteristic spindown ages older than 300 years and are within the range of theoretical predictions for possible neutron-star ellipticities. An important feature of this search was use of a barycentric resampling algorithm which substantially reduced computational cost; this method is used extensively in searches of Advanced LIGO and Virgo detector data.
a b s t r a c tAtomization plays an important role in combustion and propulsion systems, including applications in transportation and power generation. The uncertainties in oil supply and environmental concerns motivate the development of new combustion technologies using biofuels, capable of operating with high thermal efficiency, low operational cost and reduced environmental impact. Flameless combustion is a promising technology that allows the reduction of pollutant emissions with high combustion efficiency. This work describes the characteristics of soy methyl ester (SME) sprays produced by a blurry injector. Characteristics droplet diameters, discharge coefficients, air-to-liquid mass ratios, air and liquid pressures and spray cone angles were experimentally determined. Three nozzle tip configurations have been tested: cylindrical, conical and conical-cylindrical. All nozzles configurations have presented high atomization efficiency, yielding relatively small characteristics diameters (SMD and MMD) and narrow spray cone angles, favoring its application in compact combustion systems.
A simplified method is used to determine the optimum water content in the flue gases of charcoal gasifiers to be utilized as alternative fuels in the operation of engines and gas turbines for power generation. Computational models of plug flow reactors and well stirred reactors are employed to simulate the reaction and post-flame zones, adopting different chemical mechanisms. In the simulations reactants enter the reactors at 1000 K, 1 atm and equivalence ratio 0.25. It was observed that mixtures about 3% to 4% in volume of water vapor allow to obtain optimal operation characteristics, including high blowout limit, low ignition delay, maximum reaction zone temperature, high CO2 prodution and low thermal NO formation. It was observed that increasing water contents reduce significantly ignition times up to 3% in volume, while blowout mass flow rates increase continuously up to 6 % in volume, the maximum value considered. Formation of NO decreases continuously with humidity after the flame zone, while there are peaks of NO formation within the flame zone below 1% in volume. Higher water vapor content decreases the final temperatures below 1700 K, leading to a lower thermal efficiency. The method can be used to estimate optimum operational conditions with other input parameters
This work determines the preliminary mass distribution of hybrid rockets using 98% H2O2 and solid paraffin mixed with aluminum as propellants. An iterative process is used tocalculate the rocket performance characteristics and to determine the inert mass fractionfrom given initial conditions. It is considered a mission to place a 20 kg payload into a 300 km circular equatorial orbit by air launched and ground launched hybrid rockets usingthree stages. The results indicate total initial masses of about 7800 kg for a groundlaunched hybrid rocket and 4700 kg for an air launched hybrid rocket
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