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761.
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
762.
B. A. Klumov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(12):169-172
The process of the disturbance formation and evolution in the ionosphere of the Earth with a pulsed source of X-ray radiation is studied. The region of altitudes H > 100km, where nonlocal effects are essential, is examined. The formation of current system developed by noncompensated photoelectron flows is studied in detail. Time characteristics of the photoelectron flows leaving the ionosphere are calculated. A possibility of the plasma turbulence excitation by these fluxes is analyzed. 相似文献
763.
1997年 1月 10日磁暴期间, Geotail卫星在向阳侧的磁鞘中观测到了磁层氧离子突增事件.这些氧离子的出现和磁鞘中存在很强的南向行星际磁场有关.事件期间向阳面发生了准静态的磁重联,氧离子流存在由北向南的速度分量.通量突增过程具有逆向和正向能量色散现象,磁层内部只有氧离子有可能被梯度漂移输送到重联区,所以只有氧离子在磁鞘中持续地被观测到.估计氧离子的逃逸速率为 0.61× 1023/s,大约为环电流氧离子输入率的 33%.大量的环电流氧离子由磁层跑到了磁鞘,导致环电流指数 ASY-H呈现明显的非对称性. 相似文献
764.
Tomographic determination of the spatial distribution of water vapor using GPS observations 总被引:1,自引:0,他引:1
M. Troller A. Geiger E. Brockmann J.-M. Bettems B. Bürki H.-G. Kahle 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,37(12):2211-II
With the advent of the GPS navigation system, a promising ground based technique has been introduced which makes it possible to estimate the amount of water vapor in the troposphere from operational GPS networks at relatively low additional costs. While the estimation of the integrated amount is currently well established, the determination of the spatial water vapor distribution and its temporal variation are still a major challenge. To account for the vertical resolution, several tomographic approaches were pursued. We developed the software package AWATOS (atmospheric water vapor tomography software) which is based on the assimilation of double differenced GPS observations. Applying a least-squares inversion, the inhomogeneous spatial distribution of water vapor is determined. An extensive investigation has been carried out in Switzerland. GPS measurements are performed by the dense permanent Swiss national GPS network AGNES of the Swiss Federal Office of Topography (swisstopo). A total of 40 equally distributed water vapor profiles have been estimated on an hourly basis. For the purpose of validation, 22 radiosonde profiles were used at the GPS and meteorological station Payerne. Furthermore, data of the numerical weather model aLMo (alpine model in Switzerland, MeteoSwiss) were compared with the tomographic results. An overall good agreement of the three methods with an rms of better than 1.6 g/m3 absolute humidity was achieved. The results show that AGNES can be used as a dedicated network for the purpose of GPS-tomography, using a horizontal resolution of approximately 50 km and height layers of 300–500 m thickness in the lower troposphere. 相似文献
765.
Cytogenetic studies of blood lymphocytes from cosmonauts after long-term space flights on Mir station. 总被引:9,自引:0,他引:9
B Fedorenko S Druzhinin L Yudaeva V Petrov Y Akatov G Snigiryova N Novitskaya V Shevchenko A Rubanovich 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(2):355-359
Long-term space missions may increase risks of unfavorable consequences for cosmonauts as a result of radiation effects. This paper presents results of a study of cytogenetic damage in cosmonauts' peripheral blood lymphocytes induced by space radiation. Cultivation of lymphocytes and analysis of chromosomal aberrations were made according to generally accepted methods. It is shown that the yields of dicentrics and centric rings scored after long-term space flights are considerably higher than those scored prior to the flights. An attempt was made to assess individual doses received by cosmonauts. Individual biodosimetry doses received by cosmonauts who showed a reliable increase in the yields of chromosomal-type aberrations after their first flights were estimated to be from 0.02 to 0.28 Gy. 相似文献
766.
冷轧体心立方IF钢中剪切带的形成 总被引:1,自引:0,他引:1
剪切带是在高应变时冷轧金属中形成的重要微观结构,这种微结构与塑性变形行为有密切关系。本文基于塑性变形理论,运用T ay lor弛豫模型、B ishop和H ill最大功原理,对变形体心立方晶体中滑移系上的切应变分布进行了计算。计算结果表明:当晶粒的轧制方向平行于〈1 1 2〉和轧制面法向平行于〈1 1 1〉冷轧时,几乎全部切应变都能聚集在某一滑移面上,这一高度局域性的切应变是形成剪切带的原因。此时,剪切带与轧制方向之间夹角为35°。而对其他取向的晶体,切应变却呈均匀分布,因而不产生剪切带。透射电子显微镜观察到的剪切带所在晶粒的取向和所在的滑移面证实了这一剪切带的形成机制。 相似文献
767.
利用喷气装置卸载航天器积累角动量的最小工质损耗控制 总被引:1,自引:0,他引:1
讨论利用喷气装置卸载航天器积累的外扰角动量过程中 ,实现最小工质损耗的问题。提出了在航天器绕自己质心转动的过程中实现对这一角动量进行卸载的新思路。文中采用极大值原理求得了最优工质损耗并举出了实例 相似文献
768.
B. N. Korchuganov G. G. Dol'nikov M. V. Gerasimov O. F. Prilutskii R. Rider G. Waenke T. Economou 《Cosmic Research》2004,42(1):19-22
A theoretical and experimental feasibility study of possible determination of the hydrogen and deuterium concentrations in the surface layers of planetary bodies is presented. The method under study is the recoil proton and deuteron spectrometry of forward scattering in the course of elastic interaction of alpha particles with the nuclei of hydrogen isotopes. The spectra of recoil protons and deuterons were recorded using a prototype model of a hydrogen spectrometer, and these spectra were used to determine the hydrogen concentrations in the samples of different compositions. 相似文献
769.
Six-month space greenhouse experiments--a step to creation of future biological life support systems
Ivanova TN Kostov PT Sapunova SM Dandolov IW Salisbury FB Bingham GE Sytchov VN Levinskikh MA Podolski IG Bubenheim DB Jahns G 《Acta Astronautica》1998,42(1-8):11-23
SVET Space Greenhouse (SG)--the first automated facility for growing of higher plants in microgravity was designed in the eighty years to be used for the future BLSS. The first successful experiment with vegetables was carried out in 1990 on the MIR Space Station (SS). The experiments in SVET SG were resumed in 1995, when an American Gas Exchange Measurement System (GEMS) was added. A three-month wheat experiment was carried out as part of MIR-SHUTTLE'95 program. SVET-2 SG Bulgarian equipment of a new generation with optimised characteristics was developed (financed by NASA). The new SVET-GEMS equipment was launched on board the MIR SS and a successful six-month experiments for growing up of two crops of wheat were conducted in 1996 - 97 as part of MIR-NASA-3 program. The first of these "Greenhouse" experiments (123 days) with the goal to grow wheat through a complete life cycle is described. Nearly 300 heads developed but no seeds were produced. A second crop of wheat was planted and after 42 days the plants were frozen for biochemical investigations. The main environmental parameters during the six-month experiments in SVET (substrate moisture and lighting period) are given. The results and the contribution to BLSS are discussed. 相似文献
770.
Roger C. Wiens Daniel B. Reisenfeld Chad Olinger Peter Wurz Veronika S. Heber Donald S. Burnett 《Space Science Reviews》2013,175(1-4):93-124
The Genesis mission Solar Wind Concentrator was built to enhance fluences of solar wind by an average of 20x over the 2.3 years that the mission exposed substrates to the solar wind. The Concentrator targets survived the hard landing upon return to Earth and were used to determine the isotopic composition of solar-wind—and hence solar—oxygen and nitrogen. Here we report on the flight operation of the instrument and on simulations of its performance. Concentration and fractionation patterns obtained from simulations are given for He, Li, N, O, Ne, Mg, Si, S, and Ar in SiC targets, and are compared with measured concentrations and isotope ratios for the noble gases. Carbon is also modeled for a Si target. Predicted differences in instrumental fractionation between elements are discussed. Additionally, as the Concentrator was designed only for ions ≤22 AMU, implications of analyzing elements as heavy as argon are discussed. Post-flight simulations of instrumental fractionation as a function of radial position on the targets incorporate solar-wind velocity and angular distributions measured in flight, and predict fractionation patterns for various elements and isotopes of interest. A tighter angular distribution, mostly due to better spacecraft spin stability than assumed in pre-flight modeling, results in a steeper isotopic fractionation gradient between the center and the perimeter of the targets. Using the distribution of solar-wind velocities encountered during flight, which are higher than those used in pre-flight modeling, results in elemental abundance patterns slightly less peaked at the center. Mean fractionations trend with atomic mass, with differences relative to the measured isotopes of neon of +4.1±0.9 ‰/amu for Li, between ?0.4 and +2.8 ‰/amu for C, +1.9±0.7‰/amu for N, +1.3±0.4 ‰/amu for O, ?7.5±0.4 ‰/amu for Mg, ?8.9±0.6 ‰/amu for Si, and ?22.0±0.7 ‰/amu for S (uncertainties reflect Monte Carlo statistics). The slopes of the fractionation trends depend to first order only on the relative differential mass ratio, Δm/m. This article and a companion paper (Reisenfeld et al. 2012, this issue) provide post-flight information necessary for the analysis of the Genesis solar wind samples, and thus serve to complement the Space Science Review volume, The Genesis Mission (v. 105, 2003). 相似文献