4,173 research outputs found
Impact resistance of spar-shell composite fan blades
Composite spar-shell fan blades for a 1.83 meter (6 feet) diameter fan stage were fabricated and tested in a whirling arm facility to evaluate foreign object damage (FOD) resistance. The blades were made by adhesively bonding boron-epoxy shells on titanium spars and then adhesively bonding an Inconel 625 sheath on the leading edge. The rotating blades were individually tested at a tip speed of 800 feet per second. Impacting media used were gravel, rivets, bolt, nut, ice balls, simulated birds, and a real bird. Incidence angles were typical of those which might be experienced by STOL aircraft. The tests showed that blades of the design tested in this program have satisfactory impact resistance to small objects such as gravel, rivets, nuts, bolts, and two inch diameter ice balls. The blades suffered nominal damage when impacted with one-pound birds (9 to 10 ounce slice size). However, the shell was removed from the spar for a larger slice size
How to fool a virgin: Artificial dealation triggers oviposition in virgin Lasius niger queens
Once inseminated, ant queens rapidly shed their wings and start to lay eggs. Here we test whether there is a causal link between dealation and oviposition in the ant Lasius niger. We show that artificially dealated virgin queens start to lay eggs shortly after wing removal, whereas winged virgin queens hardly ever lay eggs. Dealate virgins do, however, produce fewer eggs than mated queens. These findings indicate that dealation does induce egg-laying, and that other factors, such as mating and/or insemination, further stimulate oviposition under natural conditions
Bridging the Gap Between Scientists and Classrooms: Scientist Engagement in the Expedition Earth and Beyond Program
Teachers in today s classrooms need to find creative ways to connect students with science, technology, engineering, mathematics (STEM) experts. These STEM experts can serve as role models and help students think about potential future STEM careers. They can also help reinforce academic knowledge and skills. The cost of transportation restricts teachers ability to take students on field trips exposing them to outside experts and unique learning environments. Additionally, arranging to bring in guest speakers to the classroom seems to happen infrequently, especially in schools in rural areas. The Expedition Earth and Beyond (EEAB) Program [1], facilitated by the Astromaterials Research and Exploration Science (ARES) Directorate Education Program at the NASA Johnson Space Center has created a way to enable teachers to connect their students with STEM experts virtually. These virtual connections not only help engage students with role models, but are also designed to help teachers address concepts and content standards they are required to teach. Through EEAB, scientists are able to actively engage with students across the nation in multiple ways. They can work with student teams as mentors, participate in virtual student team science presentations, or connect with students through Classroom Connection Distance Learning (DL) Events
A Theoretical Model for the Relation for Supermassive Black Holes in Galaxies
We construct a model for the formation of black holes within galactic bulges.
The initial state is a slowly rotating isothermal sphere, characterized by
effective transport speed \aeff and rotation rate . The black hole
mass is determined when the centrifugal radius of the collapse flow exceeds the
capture radius of the central black hole. This model reproduces the observed
correlation between black hole masses and galactic velocity dispersions, \mbh
\approx 10^8 M_\odot (\sigma/200 \kms)^4, where \sigma = \sqrt{2} \aeff.
This model also predicts the ratio \mrat of black hole mass to host mass:
\mrat 0.004 (\sigma/200 \kms).Comment: 9 pages, 2 figures, submitted to Astrophysical Journal Letter
Operational Improvements From the In-Trail Procedure in the North Atlantic Organized Track System
This paper explains the computerized batch processing experiment examining the operational impacts of the introduction of Automatic Dependent Surveillance-Broadcast (ADS-B) equipment and the In-Trail Procedure (ITP) to the North Atlantic Organized Track System (NATOTS). This experiment was conducted using the Traffic Manager (TMX), a desktop simulation capable of simulating airspace environments and aircraft operations. ADS-B equipment can enable the use of new ground and airborne procedures, such as the ITP. The ITP is among the first of these new procedures, which will make use of improved situation awareness in the local surrounding airspace of ADS-B equipped aircraft to enable more efficient oceanic flight level changes. The data collected were analyzed with respect to multiple operationally relevant parameters including fuel burn, request approval rates, and the distribution of fuel savings. This experiment showed that through the use of ADS-B or ADS-B and the ITP that operational improvements and benefits could be achieved
Artemis Curation: Preparing for Sample Return from the Lunar South Pole
Space Policy Directive-1 mandates that the United States will lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations. In addition, the Vice President stated that It is the stated policy of this administration and the United States of America to return American astronauts to the Moon within the next five years, that is, by 2024. These efforts, under the umbrella of the recently formed Artemis Program, include such historic goals as the flight of the first woman to the Moon and the exploration of the lunar south-polar region. Among the top priorities of the Artemis Program is the return of a suite of geologic samples, providing new and significant opportunities for progressing lunar science and human exploration. In particular, successful sample return is necessary for understanding the history of volatiles in the Solar System and the evolution of the Earth-Moon system, fully constraining the hazards of the lunar polar environment for astronauts, and providing the necessary data for constraining the abundance and distribution of resources for in-situ resource utilization (ISRU). Here we summarize the ef-forts of the Astromaterials Acquisition and Curation Office (hereafter referred to as the Curation Office) to ensure the success of Artemis sample return (per NASA Policy Directive (NPD) 7100.10E)
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