17,996 research outputs found
POTENTIAL EFFECTS OF NEW CARIBBEAN-AREA WINTER FRESH TOMATO AND CUCUMBER SUPPLIES ON THE U.S. INDUSTRY
Crop Production/Industries,
Experimental aerodynamic performance of advanced 40 deg-swept 10-blade propeller model at Mach 0.6 to 0.85
A propeller designated as SR-6, designed with 40 deg of sweep and 10 blades to cruise at Mach 0.8 at an altitude of 10.7 km (35,000 ft), was tested in the NASA Lewis Research Center's 8- by 6-Foot Wind Tunnel. This propeller was one of a series of advanced single rotation propeller models designed and tested as part of the NASA Advanced Turboprop Project. Design-point net efficiency was almost constant to Mach 0.75 but fell above this speed more rapidly than that of any previously tested advanced propeller. Alternative spinners that further reduced the near-hub interblade Mach numbers and relieved the observed hub choking improved performance above Mach 0.75. One spinner attained estimated SR-6 Design-point net deficiencies of 80.6 percent at Mach 0.75 and 79.2 percent at Mach 0.8, higher than the measured performance of any previously tested advanced single-rotation propeller at these speeds
Some effects of small-scale metallicity variations in cooling flows
In an attempt to reconcile recent spectral data with predictions of the
standard cooling flow model, it has been suggested that the metals in the
intracluster medium (ICM) might be distributed inhomogeneously on small scales.
We investigate the possible consequences of such a situation within the
framework of the cooling flow scenario. Using the standard isobaric cooling
flow model, we study the ability of such metallicity variations to
preferentially suppress low-temperature line emission in cooling flow spectra.
We then use simple numerical simulations to investigate the temporal and
spatial evolution of the ICM when the metals are distributed in such a fashion.
Simulated observations are used to study the constraints real data can place on
conditions in the ICM. The difficulty of ruling out abundance variations on
small spatial scales with current observational limits is emphasized. We find
that a bimodal distribution of metals may give rise to interesting effects in
the observed abundance profile, in that apparent abundance gradients with
central abundance drops and off-centre peaks, similar to those seen recently in
some clusters, are produced. Different elements behave in different fashion as
governed by the temperature dependence of their equivalent widths. Our overall
conclusion is that, whilst this process alone seems unlikely to be able to
account for the sharp reduction in low temperature emission lines seen in
current spectral data, a contribution at some level is possible and difficult
to rule out. The possibility of small-scale metallicity variations should be
considered when analysing high resolution cluster X-ray spectra.Comment: 14 pages, 10 figures. Accepted for publication in MNRA
Investigation of the Quantitative Determination of Point and Areal Precipitation by Radar Echo Measurements: Fourth Quarterly Technical Report
published or submitted for publicationis peer reviewedOpe
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