磁暴对海南地区电离层扩展F的影响

利用2002年2月至2007年12月海南地区DPS-4测高仪观测数据, 用统计分析方法研究了磁暴对电离层扩展F的影响. 结果认为磁暴从整体上抑制了扩展F现象的发生. 但若把扩展F分为不同类型, 则结果却有所不同. 对于频率型(FSF), 在2002年和2003年磁暴对其有促发作用, 在2004---2007年有抑制作用; 对于区域型(RSF), 在2002---2005年磁暴对其有抑制作用, 在2006年和2007年, 对其有弱促发作用; 对于混合型(MSF), 在2002年磁暴对其有抑制作用, 在2003年和2004年有促发作用, 从2005年开始, 磁暴对其有抑制作用; 对于强区域型 (SSF), 在2002---2004年磁暴对其有抑制作用, 在2005年和2006年有促发作用, 2007年有弱抑制作用.     

Numerical modeling of large elastoplastic strains in terms of principal stretches. II. Physical relations,calculation algorithm

The constitutive relations and plastic flow rule are derived from the thermodynamics equations. The known procedures of determining the plastic strain rate value are described. A calculation algorithm is presented that is based on the incremental loading, linearization of the virtual power equation and the projection method. A numerical example is presented.     

Pioneer 10 Doppler data analysis: Disentangling periodic and secular anomalies

This paper reports the results of an analysis of the Doppler tracking data of Pioneer probes which did show an anomalous behaviour. A software has been developed for the sake of performing a data analysis as independent as possible from that of Anderson et al. [Anderson, J., Laing, P.A., Lau, E.L., Liu, A.S., Nieto, M.M., Turyshev, S.G. Study of the anomalous acceleration of Pioneer 10 and 11. Phys. Rev. D 65, 082004, 2002], using the same data set. A first output of this new analysis is a confirmation of the existence of a secular anomaly with an amplitude about 0.8 nm s⁻² compatible with that reported by Anderson et al. A second output is the study of periodic variations of the anomaly, which we characterize as functions of the azimuthal angle φ$\phi$ defined by the directions Sun–Earth Antenna and Sun-Pioneer. An improved fit is obtained with periodic variations written as the sum of a secular acceleration and two sinusoids of the angles φ$\phi$ and 2φ$2\phi$. The tests which have been performed for assessing the robustness of these results are presented.     

Possibilities of parallel calculations in solving gas dynamics problems in the CFD environment of FLUENT software

The results of studying an incompressible gas flow field in a periodic element of the porous structure made up of the same radius spheres are presented; the studies were based on the solution of the Navier-Stokes equations using FLUENT software. The possibilities to accelerate the solution process with the use of parallel calculations are investigated and the calculation results under changes of pressure differential in the periodic element are given.     

Numerical modelling of radiance of the presumed dust torus around Mars in the 0.350-1 μm spectral range

Currently conducted studies on modelling of scattered solar radiation in the 0.350-1.00 μm range along the Phobos orbit around Mars are presented. Our calculations include various types of grains, various densities and scattering angles. The calculations are performed with the aid of LOWTRAN7 program. These studies are directly related to the photometer coupled to PFS (Planetary Fourier Spectrometer) planned for the Mars-96 mission.     

MMS星座对磁层顶磁通量绳内离子惯性尺度结构的观测

利用MMS观测数据,对磁层顶通量绳内离子惯性尺度（d_i）的结构进行分析研究.结果发现,许多不同尺度（约1d_i至数十d_i）的通量绳内都存在具有d_i尺度的电流 j _m,其方向在磁层顶局地坐标系的-M方向,即与磁层顶查普曼-费拉罗电流同向,由电子在+M方向的运动（ v _em）携带.这些电流结构具有以下特征：磁鞘与磁层成分混合,磁场为开放形态;离子去磁化,电子与磁场冻结;N方向（即垂直于磁层顶电流片方向）的电场 E _n显著增大,幅度达到约20mV·m^-1,并伴有明显的尖峰状起伏,该增强和尖峰状起伏的电场对应于霍尔电场.分析表明,电流、电子与离子运动的偏离以及霍尔电场之间遵从广义欧姆定律,三者密切关联.进一步对磁层顶磁重联的探测数据进行分析发现,在很多重联区内也存在与通量绳内相似的结构,其尺度约为d_i量级,其中霍尔电场 E _N、电流 j _M和电子速度 v _eM均与通量绳内对应物理量的方向相同且幅度相近.基于上述观测事实,采用经典FTE通量绳模型,对通量绳内电流、电子运动和霍尔电场的起源进行了初步探讨,认为其来源于磁层顶无碰撞磁重联区内的相应结构,并且后者在离子尺度通量绳的形成过程中起到重要作用.     

Far ultraviolet imaging from the IMAGE spacecraft. 2. Wideband FUV imaging

The Far Ultraviolet Wideband Imaging Camera (WIC) complements the magnetospheric images taken by the IMAGE satellite instruments with simultaneous global maps of the terrestrial aurora. Thus, a primary requirement of WIC is to image the total intensity of the aurora in wavelength regions most representative of the auroral source and least contaminated by dayglow, have sufficient field of view to cover the entire polar region from spacecraft apogee and have resolution that is sufficient to resolve auroras on a scale of 1 to 2 latitude degrees. The instrument is sensitive in the spectral region from 140–190 nm. The WIC is mounted on the rotating IMAGE spacecraft viewing radially outward and has a field of view of 17° in the direction parallel to the spacecraft spin axis. Its field of view is 30° in the direction perpendicular to the spin axis, although only a 17°×17° image of the Earth is recorded. The optics was an all-reflective, inverted Cassegrain Burch camera using concentric optics with a small convex primary and a large concave secondary mirror. The mirrors were coated by a special multi-layer coating, which has low reflectivity in the visible and near UV region. The detector consists of a MCP-intensified CCD. The MCP is curved to accommodate the focal surface of the concentric optics. The phosphor of the image intensifier is deposited on a concave fiberoptic window, which is then coupled to the CCD with a fiberoptic taper. The camera head operates in a fast frame transfer mode with the CCD being read approximately 30 full frames (512×256 pixel) per second with an exposure time of 0.033 s. The image motion due to the satellite spin is minimal during such a short exposure. Each image is electronically distortion corrected using the look up table scheme. An offset is added to each memory address that is proportional to the image shift due to satellite rotation, and the charge signal is digitally summed in memory. On orbit, approximately 300 frames will be added to produce one WIC image in memory. The advantage of the electronic motion compensation and distortion correction is that it is extremely flexible, permitting several kinds of corrections including motions parallel and perpendicular to the predicted axis of rotation. The instrument was calibrated by applying ultraviolet light through a vacuum monochromator and measuring the absolute responsivity of the instrument. To obtain the data for the distortion look up table, the camera was turned through various angles and the input angles corresponding to a pixel matrix were recorded. It was found that the spectral response peaked at 150 nm and fell off in either direction. The equivalent aperture of the camera, including mirror reflectivities and effective photocathode quantum efficiency, is about 0.04 cm². Thus, a 100 Rayleigh aurora is expected to produce 23 equivalent counts per pixel per 10 s exposure at the peak of instrument response.     

Integration test project of CEEF--a test bed for Closed Ecological Life Support Systems.

CEEF (Closed Ecology Experiment Facilities) were installed at Rokkasho village in northern Japan, for the purpose of clarifying life-support mechanisms in a completely closed space, such as a Lunar or Mars base. An integration test using the Closed Plantation Experiment Facility and Closed Animal Breeding & Habitation Experiment Facility is needed before conducting an entire closed experiment including plants, animals and humans. These integration tests are planned to be conducted step by step from fiscal 2001 to 2008.