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141.
Igor S. Veselovsky Serge Koutchmy 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Several important issues are open in the field of solar variability and they wait their solution which up to now was attempted using critical ground-based instrumentations. However, accurate photometric data are attainable only from space. New observational material should be collected with high enough spatial and spectral resolution, covering the whole visible range of the electromagnetic spectrum as well infrared and ultraviolet to reconstruct the total solar irradiance: (1) the absolute contributions of different small-scale structural entities of the solar atmosphere from the white light flares and from micro-flares are still poorly known; (2) we do not know the absolute contributions of different structural elements of the solar atmosphere to the long-term and to the cyclic variations of the solar irradiance, including features of the polar regions of the Sun; (3) the variations of the chromospheric magnetic network are still poorly evaluated; (4) only scarce information is available about the spectral variations of different small-scale features in the high photosphere. Variability of the Sun in white light can be studied with higher spectral, spatial and time resolution using space-born telescopes, which are more appropriate for this purpose than ground based observatories because of better seeing conditions, no interference of the terrestrial atmosphere and a more precise calibration procedure. Scientific requirements for such observations and the possible experimental tools proposed for their solution. Suggested solar studies have broader astrophysical importance. 相似文献
142.
分析了用试验机进行力学性能检定过程中,夹具的质量对标准测力仪造成的影响,并通过分析原因,给出消除或减小这种影响的方法。 相似文献
143.
克服旋转飞行器螺旋运动的方法研究 总被引:1,自引:0,他引:1
旋转飞行器虽然具有内在稳定性,但在飞行过程中一些不确定因素会导致飞行器产生螺旋运动,而非理想的关于角动量矢量纯粹的旋转运动。结合旋转飞行器自身的特点,借鉴自旋卫生的被动章动阻尼的方法,提出了一种通过主动控制飞行器内部质量块的运动使得飞行器碑的惯量主轴发生偏移,惯量矩阵由原来的对称阵变为含有非零非对角元素的矩阵,从而改变飞行器的姿态角运动来克服螺旋运动的方法,这将有助于提高旋转飞行器的资态控制精度。以某型旋转飞行器为背景进行仿真研究,计算结果证实了该方法的有效性和可行性。 相似文献
144.
面向大规模定制的产品设计的一种模型 总被引:2,自引:0,他引:2
大规模定制 (MassCustomization)环境下对产品设计的基本要求是模块化,通过模块化构件重组快速设计个性化产品,这对传统的产品设计方式提出了挑战。给出一种大规模定制环境下的产品设计模型,通过逐层分解产品的物料清单 (BOM)和工序集,动态计算个性化产品的最终物料清单、工艺路线以及对相应生产资源的需要,并且这种产品设计模型符合适合准时制 (JustInTime)生产方式的需要。 相似文献
145.
146.
H. Balsiger K. Altwegg P. Bochsler P. Eberhardt J. Fischer S. Graf A. Jäckel E. Kopp U. Langer M. Mildner J. Müller T. Riesen M. Rubin S. Scherer P. Wurz S. Wüthrich E. Arijs S. Delanoye J. De Keyser E. Neefs D. Nevejans H. Rème C. Aoustin C. Mazelle J.-L. Médale J. A. Sauvaud J.-J. Berthelier J.-L. Bertaux L. Duvet J.-M. Illiano S. A. Fuselier A. G. Ghielmetti T. Magoncelli E. G. Shelley A. Korth K. Heerlein H. Lauche S. Livi A. Loose U. Mall B. Wilken F. Gliem B. Fiethe T. I. Gombosi B. Block G. R. Carignan L. A. Fisk J. H. Waite D. T. Young H. Wollnik 《Space Science Reviews》2007,128(1-4):745-801
The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) will answer important questions posed by the mission’s
main objectives. After Giotto, this will be the first time the volatile part of a comet will be analyzed in situ. This is
a very important investigation, as comets, in contrast to meteorites, have maintained most of the volatiles of the solar nebula.
To accomplish the very demanding objectives through all the different phases of the comet’s activity, ROSINA has unprecedented
capabilities including very wide mass range (1 to >300 amu), very high mass resolution (m/Δ m > 3000, i.e. the ability to resolve CO from N2 and 13C from 12CH), very wide dynamic range and high sensitivity, as well as the ability to determine cometary gas velocities, and temperature.
ROSINA consists of two mass spectrometers for neutrals and primary ions with complementary capabilities and a pressure sensor.
To ensure that absolute gas densities can be determined, each mass spectrometer carries a reservoir of a calibrated gas mixture
allowing in-flight calibration. Furthermore, identical flight-spares of all three sensors will serve for detailed analysis
of all relevant parameters, in particular the sensitivities for complex organic molecules and their fragmentation patterns
in our electron bombardment ion sources. 相似文献
147.
We present helium and CNO isotopic yields for massive mass-losing stars in the initial mass range 15M
M
i 50M
. We investigate their dependence on assumptions about mass loss rates, internal mixing processes, and metallicity, and specify the contributions from stellar winds and from supernova ejecta. 相似文献
148.
G. M. Mason 《Space Science Reviews》2007,130(1-4):231-242
3He-rich solar energetic particle (SEP) events show huge enrichments of 3He and association with kilovolt electrons and Type-III radio bursts. Observations from a new generation of high resolution
instruments launched on the Wind, ACE, Yohkoh, SOHO, TRACE, and RHESSI spacecraft have revealed many new properties of these
events: the particle energy spectra are found to be either power-law or curved in shape, with the 3He spectrum often being distinctly different from other species. Ultra-heavy nuclei up to >200 amu are found to be routinely
present at average enrichments of >200 times solar-system abundances. The high ionization states previously observed near
∼1 MeV/nucleon have been found to decrease towards normal solar coronal values in these events. The source regions have been
identified for many events, and are associated with X-ray jets and EUV flares that are associated with magnetic reconnection
sites near active regions. This paper reviews the current experimental picture and theoretical models, with emphasis on the
new insights found in the last few years. 相似文献
149.
K. Munakata T. Kuwabara J.W. Bieber P. Evenson R. Pyle S. Yasue C. Kato Z. Fujii M.L. Duldig J.E. Humble M.R. Silva N.B. Trivedi W.D. Gonzalez N.J. Schuch 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,36(12):2357-2362
We analyze the cosmic-ray anisotropy observed by a prototype network of muon detectors during geomagnetic storms associated with coronal mass ejections (CMEs). The network currently consists of multidirectional surface muon detectors at Nagoya (Japan) and Hobart (Australia), together with a prototype detector at São Martinho (Brazil) which has been in operation since March, 2001. In this report, we analyze the anisotropy recorded in both the muon detector and neutron monitor (the Spaceship Earth) networks and find significant enhancements of cosmic-ray anisotropy during geomagnetic storms. Following the analysis by Bieber and Evenson [Bieber, J.W., Evenson, P. CME geometry in relation to cosmic ray anisotropy. Geophys. Res. Lett. 25 (1998) 2955–2958] for the neutron monitor data at 10 GeV, we also derive cosmic-ray density gradients from muon data at higher-energy (50 GeV), possibly reflecting the larger-scale geometry of CMEs causing geomagnetic storms. We particularly find in some events the anisotropy enhancement clearly starting prior to the storm onset in both the muon and neutron data. This is the first result of the CME-geometry derived from simultaneous observations of the anisotropy with networks of multidirectional muon detectors and neutron monitors. 相似文献
150.
弹性测量管的振动特性决定了科氏质量流量计的测量精度.以直管科氏质量流量计为例,初步分析研究了流体脉动对其测量管振动特性的影响.建立了被测流体脉动时测量管振动的数学模型;采用Galerkin法对模型进行了处理,将模型转化为受外激励和参数激励联合作用的有耦合多自由度振动问题;用多尺度法对其进行了分析,给出了脉动流作用下科氏质量流量计测量管振动的主要频率成分,揭示了脉动流作用的机理.所得到的大部分结论与有关文献的实验结果吻合. 相似文献