窄板拉弯成形的数值分析与回弹计算

在考虑加载历史的情况下,为采用数值方法研究窄板拉弯成形,将变形区划分成若干个单元,按塑性变形体积不变条件,确定单元应变.利用增量理论,由差分方程算出应力分布,并分析了加载历史对其影响.依据卸载变形的分析计算,推导出回弹后中性层弯曲半径及弯曲角变化量的计算公式.计算结果表明,先弯曲再拉伸时应力分布规律更利于减小回弹.     

Optimal low-thrust transfers between close near-circular coplanar orbits

Four types of optimal solutions are demonstrated to exist for transfers (time of flight is not fixed) between close near-circular coplanar orbits. One solution is realized with the help of fixed orientation of the propulsion system (PS) along a transversal in the orbital coordinate system. Another is reached at fixed orientation of the PS in the inertial coordinate system. The third and fourth types of solutions change the PS orientation in the process of executing the maneuver. Regions of existence are established for all types of solutions, and algorithms for determination of parameters of these maneuvers are suggested. The algorithms were used to calculate parameters of the maneuvers of transfer from a launching orbit to a working Sun-synchronous orbit, and to calculate the maneuvers of supporting the parameters of such an orbit in a specified range.     

Sources of inner radiation zone energetic helium ions: Cross-field transport versus in-situ nuclear reactions

Radial transport theory for inner radiation zone MeV He ions has been extended by combining radial diffusive transport, losses due to Coulomb friction and charge exchange reaction with local generation of ³He and ⁴He ions due to nuclear reactions taking place on the inner edge of the inner radiation zone. From interactions between high energy trapped protons and upper atmospheric constituents we have included a nuclear reaction yield helium flux source that was numerically derived from a nuclear reaction model originally developed at the Institute of Nuclear Researches of Moscow, Russia and implemented in the computer system at the University of Campinas, Brazil. Magnetospheric transport computations have been made covering the L-shell range L=1.0 to 1.6 and the resulting MeV He ion flux distributions show a strong influence of the local nuclear source mechanism on the inner zone energetic He ion content.     

Ensuring of long operation life of the orbiting station EVA space suit

Russia has gained a lot of experience in operating the space suits (SS) during the extravehicular activities (EVA) by the crews of SALYUT-6, SALYUT-7 and MIR orbiting stations. A total of 21 Orlan-type space suits of various models were operated onboard the orbiting stations (OS) during almost 20 years period. Some of these space suits served up to 3 years in orbit. The paper reviews special features of long SS operation (without return to the Earth) onboard an orbiting station as well as the problems associated with SS repeated use by several crews. An analysis of measures to support solving of the problems of SS long stay and reliable operation onboard the orbiting station is made: selection of a corresponding SS type and separate elements design; selection of the materials; routine and preventive maintenance; development tests. The advantages of the space suit of a semi-rigid type for solving the above problems are shown. The paper includes a short analysis of space suits' operation onboard the Russian orbiting station MIR, and some restuts of inspection of the Orlan-DMA space suit returned to the Earth from orbit by STS-79 alter long operation in orbit. Recommendations on further improvement of the space suits for EVA operations in the International Space Station (ISS) are given.     

Russian system of countermeasures on board of the International Space Station (ISS): the first results

The system of countermeasures used by Russian cosmonauts in space flights on board of International Space Station (ISS) was based on the developed and tested in flights on board of Russian space stations. It included as primary components: physical methods aimed to maintain the distribution of fluids at levels close to those experienced on Earth; physical exercises and loading suits aimed to load the musculoskeletal and the cardiovascular systems; measures that prevent the loss of fluids, mainly, water-salt additives which aid to maintain orthostatic tolerance and endurance to gravitational overloads during the return to Earth; well-balanced diet and medications directed to correct possible negative reactions of the body to weightlessness. Fulfillment of countermeasure's protocols inflight was thoroughly controlled. Efficacy of countermeasures used were assessed both in- and postflight. The results of studies showed that degrees of alterations recorded in different physiological systems after ISS space flights in Russian cosmonauts were significantly higher than those recorded after flights on the Russian space stations. This phenomenon was caused by the failure of the ISS crews to execute fully the prescribed countermeasures' protocols which was as a rule excused by technical imperfectness of exercise facilities, treadmill TVIS particularly.     

Large Scale Modulation: View From the Earth

The current knowledge and ideas, obtained from groundlevel observations and concerning the solar modulation of cosmic rays, are reviewed. The following topics are discussed: observations of the cosmic ray modulation at the Earth and main characteristics of the accumulated experimental data; manifestations of the solar magnetic cycle in cosmic rays; the effect of hysteresis and its relation to the size of the heliosphere; the rigidity spectrum of long-term cosmic ray variations; the influence of the sporadic effects on long-term modulation; long-term variations of cosmic ray anisotropy and gradients; the place of groundlevel observations in current studies of cosmic ray modulation and their future prospects. Particular consideration is given to the correlation of long-term cosmic ray variations with different solar-heliospheric parameters, and to empirical models of cosmic ray modulation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Cosmic Rays in Relation to Space Weather

A review of selected experimental results relevant for the use of cosmic ray records in Space Weather research is presented. Interplanetary perturbations, initiated in the solar atmosphere, affect galactic cosmic rays. In some cases their influence on the cosmic ray intensity results in data signatures that can possibly be used to predict geomagnetic storm onsets. Case studies illustrating the complexity of the cosmic ray effects and related geomagnetic activity precursors are discussed. It is shown that some indices for cosmic ray activity are good tools for testing the reliability of cosmic ray characteristics for Space Weather forecasts. A brief summary of the influence of cosmic rays on the ozone layer is also given. The use of cosmic ray data for Space Weather purposes is still in its infant stage, but suggestions for both case and statistical studies are made. This revised version was published online in August 2006 with corrections to the Cover Date.