Numerical modeling of RadioAstron SRT temperature deformations

The results of modeling the thermal deformations of a space radio telescope’s reflecting surface are presented in the paper. Calculations were performed for the versions of the most unfavorable telescope illumination by the Sun.     

Statistical study of interplanetary condition effect on geomagnetic storms

Based on the archive OMNI data for the period 1976–2000 an analysis has been made of 798 geomagnetic storms with D _st < −50 nT and their interplanetary sources-large-scale types of the solar wind: CIR (145 magnetic storms), Sheath (96), magnetic clouds MC (62), and Ejecta (161). The remaining 334 magnetic storms have no well-defined sources. For the analysis, we applied the double method of superposed epoch analysis in which the instants of the magnetic storm beginning and minimum of D _st index are taken as reference times. The well-known fact that, independent of the interplanetary source type, the magnetic storm begins in 1–2 h after a southward turn of the IMF (B _z < 0) and both the end of the main phase of a storm and the beginning of its recovery phase are observed in 1–2 h after disappearance of the southward component of the IMF is confirmed. Also confirmed is the result obtained previously that the most efficient generation of magnetic storms is observed for Sheath before MC. On the average parameters B _z and E _y slightly vary between the beginning and end of the main phase of storms (minimum of D _st and D _st ^* indices), while D _st and D _st ^* indices decrease monotonically proportionally to integral of B _z and E _y over time. Such a behavior of the indices indicates that the used double method of superposed epoch analysis can be successfully applied in order to study dynamics of the parameters on the main phase of magnetic storms having different duration.     

Concentration of ions in the topside ionosphere as measured onboard the <Emphasis Type="Italic">DEMETER</Emphasis> satellite: Morphology and dependence on solar and geomagnetic activity

Variations in concentration of ions H⁺, He⁺, and O⁺ are studied at a height of about 700 km using the data of continuous observations onboard the DEMETER satellite at the decline and in the minimum of solar activity from 2004 to 2008. Latitudinal distributions, seasonal behavior, and irregular variations in ion concentrations and their dependence on solar and geomagnetic activity are considered. Within this altitude range, for the first time an analysis is performed of the dataset of many-year continuous observations in both hemispheres from the equatorial to subauroral latitudes. This made it possible to describe the seasonal and irregular variations of the concentrations of main ion species with better time and spatial resolution than in the available empirical models. The dependence of concentrations of three types of ions on solar and geomagnetic activity is studied at time scales from several days to several years, and it is shown that the anti-phase change in concentrations of O⁺ and light ions known from publications is partly a result of mutual dependence of solar and geomagnetic activity and is observed only at time scales beginning from several months. At time scales from several days to several weeks, variations in the concentration of O⁺ and light ions are governed mainly by solar and geomagnetic activity, respectively.     

Ballistics of a nonfragmenting meteor body with allowance made for mass outflow in the non-isothermal atmosphere. I

The paper is devoted to studying the motion of meteor bodies with mass outflow in a planet’s atmosphere, taking into account the non-isothermal character of the latter. Analytical solutions are obtained at the constant parameter of mass outflow in the model of a nonfragmenting meteoroid. A theoretical analysis of the derived regularities of the ballistics of such bodies is presented.     

叶片轴颈台阶深度专用测量装置

叶片轴颈台阶深度专用测具较好地解决了长期存在的通用量具测量叶片轴颈台阶深度测不准,效率低等问题.它采用比较法测量,操作简单,满足航空发动机叶片的测量要求.     

专访赫尔辛基市经济发展部——艾罗·豪斯提拉部长阁下

问:2010上海世博会是全球关注的一大盛事,阁下对明年的上海世博会有什么感言?答:上海2010年世博会将会是一场由世界各地知识技术荟萃而成的奇幻盛展。"城市,让生活更美好"这个主题对世界上已逾一半生活在城市里的人们来说是非常符合现实的。无论是在上海,赫尔辛基,还是在世界其他城市,我们都需要为市民创造出一个健康幸福的     

Investigation of helicopter maneuverability by the power balance method

The algorithms for calculating available overloads and maneuvers are presented. Nesterov’s loop maneuver is analyzed.     

Metal creep model with the initial strain discontinuity and functional material constants

It is proposed that curves of metal creep be approximated by the time-relative linear law with the initial creep strain discontinuity; as a result, the solution of initial boundary value rheological problems is considerably simplified and is characterized by the adequate precision with a large service life. The labor intensity of computations is similar to the steady-state creep law. The introduction of functional material constants makes it possible to perform calculations of creep under the action of temperature that is different from the specified one in the basic experiments as well as calculations of nonuniformly heated structure elements.