共查询到20条相似文献,搜索用时 39 毫秒
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《Aerospace and Electronic Systems Magazine, IEEE》1994,9(2):3-8
The following topics are dealt: career development definition; career development as a part of effective management; job satisfaction issues; motivated abilities; a case study results; identification of motivational patterns; and 'reinvention' of career development 相似文献
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《Aerospace and Electronic Systems Magazine, IEEE》2000,15(9):43-45
Cars powered by fuel cells have been built and tested; however, the aerospace fuel cells could not deliver high power quickly when the driver wanted to accelerate his car. Today's hybrid electric cars carry a battery that supplies the acceleration power, and the prime power source, whether an engine or fuel cell, is not stressed with sudden load peaks. Zero air pollution becomes attainable when fuel-cells supply the prime power on a hybrid vehicle 相似文献
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A finite element model of the Z-crimp shaping from a hard sheet blank is developed and a number of calculations using the
ANSYS finite element software is conducted. The calculations are carried out in the framework of elastoplastic behavior of
the blank material using the classical model of bilinear kinematic (translational) hardening with corresponding parameters
of elasticity and plasticity. The model takes into account kinematics of spatial transformation of the shaping equipment as
well as the time-variable conditions of its contact interaction with the blank. 相似文献
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L. I. Parfenova I. M. Zakirov A. A. Konopleva A. A. Knyazev Yu. G. Galyametdinov 《Russian Aeronautics (Iz VUZ)》2011,54(1):95-98
The techniques of injecting nanomodifiers into the sulphamate electrolyte used for electrolytic forming of nickel antiabrasive
protective tipping are considered. The optimal concentration of surfactant and nanomodifier are determined. The graphs are
also presented. 相似文献
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Based on the experience gained from Sunrayce '95, the Solar Motion Team has made many changes to the design of the next generation solar car. These changes have resulted in a vehicle that is very different from the “Solar Rolar”, The Dakota Sun is a three wheeled vehicle with separate cab and solar array. This design allows for improved aerodynamics, decreased weight, lower rolling resistance, and ease of manufacture compared to the four wheeled catamaran used in the last race. However, this design sacrifices total enclosed wheel base area, additional room for components, and added power from side solar panels, The major objectives for the team's redesigned Sunrayce '97 entry are: systems integration; decrease the weight of the car; decrease aerodynamic drag; more efficient use of available energy; and increased driver safety. The team has set a standard to use the latest available technology. Although this increases the complexity of the components, by using a systems engineering approach the “Dakota Sun” has evolved into a more integrated vehicle. This philosophy of integrated design has resulted in great improvements in mechanical design and manufacturing techniques, as well as electrical innovations. The major design changes evident from the original Sunraycen '95 vehicle are the result of an evolutionary design process that has produced the highly competitive Sunraycel '97 design outlined in this article 相似文献
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F. Bagenal A. Adriani F. Allegrini S. J. Bolton B. Bonfond E. J. Bunce J. E. P. Connerney S. W. H. Cowley R. W. Ebert G. R. Gladstone C. J. Hansen W. S. Kurth S. M. Levin B. H. Mauk D. J. McComas C. P. Paranicas D. Santos-Costa R. M. Thorne P. Valek J. H. Waite P. Zarka 《Space Science Reviews》2017,213(1-4):219-287
In July 2016, NASA’s Juno mission becomes the first spacecraft to enter polar orbit of Jupiter and venture deep into unexplored polar territories of the magnetosphere. Focusing on these polar regions, we review current understanding of the structure and dynamics of the magnetosphere and summarize the outstanding issues. The Juno mission profile involves (a) a several-week approach from the dawn side of Jupiter’s magnetosphere, with an orbit-insertion maneuver on July 6, 2016; (b) a 107-day capture orbit, also on the dawn flank; and (c) a series of thirty 11-day science orbits with the spacecraft flying over Jupiter’s poles and ducking under the radiation belts. We show how Juno’s view of the magnetosphere evolves over the year of science orbits. The Juno spacecraft carries a range of instruments that take particles and fields measurements, remote sensing observations of auroral emissions at UV, visible, IR and radio wavelengths, and detect microwave emission from Jupiter’s radiation belts. We summarize how these Juno measurements address issues of auroral processes, microphysical plasma physics, ionosphere-magnetosphere and satellite-magnetosphere coupling, sources and sinks of plasma, the radiation belts, and the dynamics of the outer magnetosphere. To reach Jupiter, the Juno spacecraft passed close to the Earth on October 9, 2013, gaining the necessary energy to get to Jupiter. The Earth flyby provided an opportunity to test Juno’s instrumentation as well as take scientific data in the terrestrial magnetosphere, in conjunction with ground-based and Earth-orbiting assets. 相似文献
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The InSight mission launches in 2018 to characterize several geophysical quantities on Mars, including the heat flow from the planetary interior. This quantity will be calculated by utilizing measurements of the thermal conductivity and the thermal gradient down to 5 meters below the Martian surface. One of the components of InSight is the Mole, which hammers into the Martian regolith to facilitate these thermal property measurements. In this paper, we experimentally investigated the effect of the Mole’s penetrating action on regolith compaction and mechanical properties. Quasi-static and dynamic experiments were run with a 2D model of the 3D cylindrical mole. Force resistance data was captured with load cells. Deformation information was captured in images and analyzed using Digitial Image Correlation (DIC). Additionally, we used existing approximations of Martian regolith thermal conductivity to estimate the change in the surrounding granular material’s thermal conductivity due to the Mole’s penetration. We found that the Mole has the potential to cause a high degree of densification, especially if the initial granular material is relatively loose. The effect on the thermal conductivity from this densification was found to be relatively small in first-order calculations though more complete thermal models incorporating this densification should be a subject of further investigation. The results obtained provide an initial estimate of the Mole’s impact on Martian regolith thermal properties. 相似文献
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The paper by Koc and Chen (1994) includes new formulas for computational complexity, but the method itself is already known and has dubious numerical stability. A poorly conditioned example is shown 相似文献
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High resolution 3D “snapshot” ISAR imaging and featureextraction 总被引:1,自引:0,他引:1
Mayhan J.T. Burrows M.L. Cuomo K.M. Piou J.E. 《IEEE transactions on aerospace and electronic systems》2001,37(2):630-642
We have developed a new formulation for three dimensional (3D) radar imaging of inverse synthetic aperture radar (ISAR) data based on recent developments in high resolution spectral estimation theory. Typically for non real-time applications, image formation is a two step process consisting of motion determination and image generation. The technique presented focuses on this latter process, and assumes the motion of the target is known. The new technique offers several advantages over conventional techniques which are based on the correlation imaging function. In particular, the technique provides for a direct 3D estimate (versus back projection to a 3D target grid matrix) of the locations of the dominant scattering centers using only a minimum set of independent 2D range-Doppler ISAR “snapshots” of the target. Because of the snapshot nature of the technique, it is particularly applicable to 3D imaging of sectors of sparse-angle data, for which the sidelobes of the correlation imaging integral become high. Furthermore, the technique provides for an estimate of amplitude and phase of each scattering center as a function of aspect angle to the target, for those aspect angles which encompass the set of 2D range-Doppler snapshots. Results illustrating the technique developed are presented for both simulated and static range data 相似文献
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