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831.
This investigation studies the effect of trailing-edge scalloping on the lift and drag force coefficients of flat, membrane wings that vibrate at low Reynolds numbers (<61,000). A series of rigid, flat plate frames with moderate aspect ratio and repeating membrane cell structure were studied and compared to a rigid plate and a rigid scalloped plate. Lift and drag measurements were acquired using an external force-balance; flow fluctuation measurements were captured with a hot-wire. Results showed that the size and aspect ratio of the latex cell had a greater impact on lift than scalloping and that scalloping had a greater effect on drag than the cell aspect ratio. Compared to the solid wings, the membrane wings exhibited higher lift and drag coefficients, likely due to both effective cambering and dynamic interaction with the free shear layer. While trailing-edge scalloping decreased both the lift and drag coefficients relative to no scalloping, the greater effect was on drag, thus, increasing aerodynamic efficiency. The maximum lift-to-drag ratio was attained for a 25% scallop with a repeating cell aspect ratio of one. A unique nondimensional scaling of the membrane vibration peak frequency is also presented. 相似文献
832.
833.
R. Goldstein S. Nikzad M. Davis R. Frahm D. Slater T.J. Jones 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We report the measurements of the response of a delta-doped Charge Coupled Device (CCD) in imaging mode to beams of charged and neutral particles. That is, the detector imaged the incident beam over its 1024 × 1024 pixels, integrating the number of particles counted in each pixel during the exposure period. In order to count individual particles the exposure time would have had to be reduced considerably compared to the typical ?5 s used in these studies. Our CCD thus operated in a different manner than do conventional particle detectors such as the CEM and MCP that normally are used in a particle counting mode. The measurements were carried out over an energy range from 0.8 to 30 keV. The species investigated include H, H+, He+, N+, N2+, and Ar+. The energy and ion mass covered wider ranges than previous measurements for the CCD. The results of these measurements show, as in the case of the previous measurement, for a given ion the CCD response increases with energy and for a given particle energy the response decreases with increasing mass of the particle. These results are in agreement with predictions of the theory of the range of ions in solids. The results also show the possibility for the application of the delta doped CCD as a detector for low energy particle measurements for space plasma physics applications. 相似文献
834.
H. Fuke N. Izutsu D. Akita I. Iijima Y. Kato J. Kawada K. Matsushima Y. Matsuzaka E. Mizuta M. Namiki N. Nonaka S. Ohta Y. Saito T. Sato M. Seo Y. Shoji A. Takada K. Tamura M. Toriumi K. Yamada T. Yamagami T. Yoshida 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The super-pressure balloon (SPB) has been expected to be a flight vehicle that can provide a long flight duration to science. Since 1997, we have developed the SPB. Now we are at the phase of developing an SPB of a practical size. In 2009, we carried out a test flight of a pumpkin-shaped SPB with a 60,000 m3 volume. The undesirable result of this flight aroused us to resolve the deployment instability of the pumpkin-shaped SPB, which has been known as one of the most challenging issues confronting SPB development. To explore this deployment issue, in 2010, we carried out a series of ground tests. From results of these tests, we found that an SPB design modified from pumpkin, named “tawara”, can be a good candidate to greatly improve the deployment stability of the lobed SPB. 相似文献
835.
R.D. Gehrz E.E. Becklin J. de Buizer T. Herter L.D. Keller A. Krabbe P.M. Marcum T.L. Roellig G.H.L. Sandell P. Temi W.D. Vacca E.T. Young H. Zinnecker 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint US/German project, is a 2.5-m infrared airborne telescope carried by a Boeing 747-SP that flies in the stratosphere at altitudes as high as 45,000 ft (13.72 km). This facility is capable of observing from 0.3 μm to 1.6 mm with an average transmission greater than 80% averaged over all wavelengths. SOFIA will be staged out of the NASA Dryden Flight Research Center aircraft operations facility at Palmdale, CA. The SOFIA Science Mission Operations (SMO) will be located at NASA Ames Research Center, Moffett Field, CA. First science flights began in 2010 and a full operations schedule of up to one hundred 8 to 10 hour-long flights per year will be reached by 2014. The observatory is expected to operate until the mid-2030s. SOFIA’s initial complement of seven focal plane instruments includes broadband imagers, moderate-resolution spectrographs that will resolve broad features due to dust and large molecules, and high-resolution spectrometers capable of studying the kinematics of atomic and molecular gas at sub-km/s resolution. We describe the SOFIA facility and outline the opportunities for observations by the general scientific community and for future instrumentation development. The operational characteristics of the SOFIA first-generation instruments are summarized. The status of the flight test program is discussed and we show First Light images obtained at wavelengths from 5.4 to 37 μm with the FORCAST imaging camera. Additional information about SOFIA is available at http://www.sofia.usra.edu and http://www.sofia.usra.edu/Science/docs/SofiaScienceVision051809-1.pdf. 相似文献
836.
Aircraft traffic management on the airport surface will require the effective utilization of communications, navigation and surveillance (CNS). This paper describes an experiment which provides a glimpse of future automation. The experiment combines precision surface radar, high-accuracy differential GPS (DGPS) position determination, automatic dependent surveillance (ADS), and ground and airborne automation systems able to intercommunicate via a VHF data link. In particular, this paper describes the air/ground communications provided by the VHF Data Link. Two classes of messages are processed: continual and ad hoc. The former include DGPS corrections, ADS messages and target data. The latter include graphical taxi clearances and hold bar set-reset information. The work described in this paper is the result of a cooperative venture among NASA, Westinghouse-Norden Systems and ARINC 相似文献
837.
J.-P. Treilhou T.V. Kozelova L.L. Lazutin V.G. Petrov I.Z. Zhulin A. Pedersen R. Pellinen W.K. Riedler G. Marklund 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(4):163-169
Measurements of the electric field in the ionosphere and the equatorial plane during the pre-onset and actives phases of a substorm (March 4, 1979) are compared. Correlations and disagrements between the measurements are considered. The preliminary conclusion is reached that the model of electrojet polarisation proposed by CORONITI and KENNEL (1972) could possibly explain part of our observations. 相似文献
838.
J T Lett A B Cox A C Lee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1986,6(11):295-303
Aspects of experiments on radiation-induced lenticular opacification during the life spans of two animal models, the New Zealand white rabbit and the rhesus monkey, are compared and contrasted with published results from a life span study of another animal model, the beagle dog, and the most recent data from the ongoing study of the survivors from radiation exposure at Hiroshima and Nagasaki. An important connection among the three animal studies is that all the measurements of cataract indices were made by one of the authors (A.C.L.), so variation form personal subjectivity was reduced to a minimum. The primary objective of the rabbit experiments (radiations involved: 56Fe, 40Ar and 20Ne ions and 60Co gamma photons) is an evaluation of hazards to astronauts from galactic particulate radiations. An analogous evaluation of hazards from solar flares during space flight is being made with monkeys exposed to 32, 55, 138 and 400 MeV protons. Conclusions are drawn about the proper use of animal models to simulate radiation responses in man and the levels of radiation-induced lenticular opacification that pose risks to man in space. 相似文献
839.
840.
An onboard astronomical system is suggested, based on the developed method using virtual measurements of zenith distances
of stars. Two algorithms of the method are described, their theory is given, and statistical results of the system’s simulation
are presented. 相似文献