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991.
The results of analyzing the stress-strain and limiting states of a main rotor blade of the Ansat helicopter in the hovering
mode are given. To estimate the strength, a technique of elastic constants variation is used; it is based on the limit equilibrium
theory and enables us to obtain the upper and lower bounds of the critical load simultaneously. Strength margin coefficients
of the blade root section are determined depending on the azimuth of a blade turn, when all generalized forces vary in proportion
to one loading parameter. 相似文献
992.
B. I. Mamaev 《Russian Aeronautics (Iz VUZ)》2011,54(4):372-378
Some design and experimental data on two series of turbine cascades with the profiles having a conventional rounded edge and
the modified profiles having the leading edge outline with continuously varied curvature are presented. The investigations
showed that such a modification can lower the profile losses in the turbine cascade by 0.2–0.4 %. 相似文献
993.
Yu. G. Markov R. R. Dasaev V. V. Perepelkin I. N. Sinitsyn V. I. Sinitsyn 《Cosmic Research》2005,43(1):52-64
A generalization of kinetic and spectral and correlation equations of fluctuations in the Earths rotation is made taking into account the effect of the Moon and planets (these equations form the basis for corresponding stochastic models). Special attention is paid to a parameterized version of kinetic equations based on the method of normal approximation. The application of linear stochastic models for obtaining the spectral and correlation characteristics of the Earths rotation is considered, including the case of random parameters of the tensor of inertia of a deformable Earth. The results can be used for constructing stochastic models of the Earths rotation over time intervals of 6–10 years.Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 1, 2005, pp. 54–66.Original Russian Text Copyright © 2005 by Markov, Dasaev, Perepelkin, I. N. Sinitsyn, V. I. Sinitsyn. 相似文献
994.
I.N. Tziavos G.S. Vergos S.P. Mertikas A. Daskalakis V.N. Grigoriadis A. Tripolitsiotis 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The use of geoid heights has been one of the available methodologies utilized for the independent calibration/validation of altimeters on-board satellites. This methodology has been employed for long in the Gavdos dedicated cal/val facility (Crete, Greece), where calibration results for the Jason satellites have been estimated, both for ascending and descending passes. The present work gives a detailed overview of the methodology followed in order to estimate a high-resolution and accuracy gravimetric geoid model for the wider Gavdos area, in support of the on-going calibration work. To estimate the geoid model, the well-known remove-compute-restore method is used while residual geoid heights are estimated through least-squares collocation so that associated errors are determined as well. It is found that the estimated formal geoid errors from LSC along passes 018 and 109 of Jason satellites, used for the bias estimation, range between ±0.8–1.6 cm. The so-derived geoid heights are employed in the determination of the Jason-2 altimeter bias for all available cycles (cycles 1-114, spanning the period from July 2008 to August 2011) together with the RioMed DOT model. From the results acquired the Jason-2 bias has been estimated to be +196.1 ± 3.2 mm for pass 109 and +161.9 ± 5.1 mm for pass 018. Within the same frame, the GOCE/GRACE-based geopotential model GOCO02s has been used to estimate the mean dynamic ocean topography and the steady-state circulation in the area around Gavdos. The so-derived DOT model was used to estimate the Jason-2 bias in an effort to evaluate the performance of satellite-only geoid models and investigate whether their spatial resolution and accuracy provides some improvement w.r.t. traditional local gravimetric geoids. From the results acquired with geoid heights from GOCO02s, the estimated Jason-2 bias deviates significantly from that of the local gravimetric model, which can be attributed to a possible mean offset and the low resolution of GOCE-based GGMs. On the other hand, when the newly estimated GOCE-based DOT was employed with geoid heights from the local gravimetric geoid model, the Jason-2 bias has been estimated to be +185.1 ± 3.2 mm for pass 109 and +130.2 ± 5.1 mm for pass 018. 相似文献
995.
A.M. Galper O. Adriani R.L. Aptekar I.V. Arkhangelskaja A.I. Arkhangelskiy M. Boezio V. Bonvicini K.A. Boyarchuk Yu.V. Gusakov M.O. Farber M.I. Fradkin V.A. Kachanov V.A. Kaplin M.D. Kheymits A.A. Leonov F. Longo P. Maestro P. Marrocchesi E.P. Mazets E. Mocchiutti A.A. Moiseev N. Mori I. Moskalenko P.Yu. Naumov P. Papini P. Picozza V.G. Rodin M.F. Runtso R. Sparvoli P. Spillantini S.I. Suchkov M. Tavani N.P. Topchiev A. Vacchi E. Vannuccini Yu.T. Yurkin N. Zampa V.G. Zverev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV–3 TeV is presented. The angular resolution of the instrument, 1–2° at Eγ ∼ 100 MeV and ∼0.01° at Eγ > 100 GeV, its energy resolution ∼1% at Eγ > 100 GeV, and the proton rejection factor ∼106 are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei. 相似文献
996.
I.A. Molotkov B. Atamaniuk A.V. Popov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Interaction of a powerful obliquely incident wave beam of decameter radio waves with the ionospheric F2 layer is analyzed. Much like the linear case, propagation through the natural anti-waveguide layer F2 splits the initial beam. Some part of its energy leaks through the ionospheric layer, the other part goes back along a downward trajectory. However, nonlinearity leads to further stratification of the ionospheric layer. A new feature, in comparison with the linear case, is appearing a narrow waveguide beneath the F2 layer maximum which traps a small part of the beam energy. We study the relationship between these parts of the wave field in a simplified model of parabolic F2 layer, with nonlinearity caused by thermal plasma expulsion from the high field intensity region. Analytical results are supplemented with numerical estimates of the effects. 相似文献
997.
X.H. Wei J.B. Cao G.C. Zhou H.S. Fu O. Santolík H. Rème I. Dandouras N. Cornilleau A. Fazakerley 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The whistler-mode waves and electron temperature anisotropy play a key role prior to and during magnetic reconnection. On August 21, 2002, the Cluster spacecrafts encountered a quasi-collisionless magnetic reconnection event when they crossed the plasma sheet. Prior to the southward turning of magnetospheric magnetic field and high speed ion flow, the whistler-mode waves and positive electron temperature anisotropy are simultaneously observed. Theoretic analysis shows that the electrons with positive temperature anisotropy can excite the whistler-mode waves via cyclotron resonances. Using the data of particles and magnetic field, we estimated the whistler-mode wave growth rate and the ratio of whistler-mode growth rate to wave frequency. They are 0.0016fce (Electron cyclotron frequency) and 0.0086fce, respectively. Therefore the whistler-mode waves can grow quickly in the current sheet. The combined observations of energetic electron beams and waves show that after the southward turning of magnetic field, energetic electrons in the reconnection process are accelerated by the whistler-mode waves. 相似文献
998.
Cerny C.L. Via G.D. Ebel J.L. DeSalvo G.C. Quach T.K. Bozada C.A. Dettmer R.W. Gillespie J.K. Jenkins T.J. Pettiford C.I. Sewell J.S. Ehret J.E. Merkel K. Wilson A. Lyke J. 《Aerospace and Electronic Systems Magazine, IEEE》1998,13(3):7-14
The requirements for space-based integrated circuit applications are defined with an emphasis on being radiation tolerant and low power consuming. Flexible analog signal processors (FASPs) are outlined as a means by which effective circuit designs can be utilized to perform a multitude of tasks. The development of complementary III-V technologies have been proven to meet the demands of the space environment, and have demonstrated the potential for frequency operation beyond 1 GHz using power supply voltages at or below 1.5 Volts. The novel fabrication process known as Xs-MET (pronounced kismet, which uses the Creek letter chi, X, and stands for Complementary Heterostructure Integrated Single Metal Transistor), is introduced as a manufacturing technique to be used in FASP design. The Xs-MET fabrication process is outlined with preliminary device results presented. An example of a FASP circuit design using Xs-MET is provided. Conclusions regarding the utilization of the Xs-MET process for FASPs are outlined with comments focusing on a space-based demonstration 相似文献
999.
P.S. Marrocchesi H.S. Ahn P. Allison M.G. Bagliesi L. Barbier J.J. Beatty G. Bigongiari T.J. Brandt J.T. Childers N.B. Conklin S. Coutu M.A. DuVernois O. Ganel J.H. Han J.A. Jeon K.C. Kim M.H. Lee L. Lutz P. Maestro A. Malinine S. Minnick S.I. Mognet S.W. Nam S. Nutter I.H. Park N.H. Park E.S. Seo R. Sina P. Walpole J. Wu J. Yang Y.S. Yoon R. Zei S.Y. Zinn 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(12):2002-2009
Launched from McMurdo (Antarctica) in December 2005, the balloon experiment CREAM (cosmic ray energetics and mass) collected about 15 million triggers during its second flight of 28 days. Redundant charge identification, by two pixelated silicon arrays and a time resolved pulse shaping technique from a scintillator system, allowed a clear signature of the primary nuclei. The energy was measured with a tungsten/SciFi calorimeter preceded by a graphite target. Preliminary results from the analysis of the data of the second flight are presented. 相似文献
1000.
I. Ueno K. Kochiya 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(12):2089-2093
Particle motion in a volatile droplet on a solid surface, especially the behavior of particles depositing in the vicinity of a solid–liquid–gas boundary line (contact line) is focused. This phenomenon is called the ‘coffee stain problem’. Motion and deposition of the particles suspended in distilled water droplets and distilled water–ethanol mixture droplets are discussed. The spatio-temporal particle motion is analyzed by the three-dimensional particle tracking velocimetry (3D PTV). A discussion of the morphology of the particles stuck to the solid surface after the dryout of the droplet is also given. 相似文献