Solar System Ionospheres

This article reviews our understanding of the ionospheres in the solar system. It provides some basic information on the sources and sinks of the ionospheric plasma, its dynamics, the energetics and the coupling to the neutral atmosphere. Ionospheres in the solar system are reviewed and comparative ionospheric topics are discussed.     

Flares of August 1972: Analysis of dynamics

The optical observations and analyses of the flares of August 1972 are reviewed with emphasis on their dynamics. In particular, various assessments are made of possible quantitative interpretation of observed data. Specific topics considered are the storage and release of magnetic energy, triggering mechanisms, particle acceleration and magnetic field reconnection, and coronal and solar wind responses. Supplemental discussions on possible future direction of research are presented, illustrating the need for examination of the storage and release of flare energy in the lower solar atmosphere.On leave from the High Altitude Observatory.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

The dynamics of the atmospheres of the major planets

The literature on the dynamics of Jupiter's atmosphere is reviewed and used as a basis for suggesting what observations would yield useful information about Jovian Dynamics. The atmospheres of Saturn, Uranus and Neptune are discussed from the same point of view.This is one of the publications by the Science Advisory Group.     

Current knowledge of Venus

As an introduction to the remaining papers in this issue, a summary is given of our current knowledge of Venus, with emphasis on recent progress and on the contributions to be expected from the Pioneer Venus missions. Headings are surface and interior, clouds and lower atmosphere, dynamics and thermal structure, neutral upper atmosphere, and ionosphere and solar-wind cavity.     

Imaging diagnostics of solar non-thermal particles

Non-thermal hard X-ray, gamma-ray and radio emission are the most direct signatures of the presence of energetic particles in the solar atmosphere. This paper lays emphasis on hard X-ray and radio imaging data, obtained during and outside flares, which reveal the sites where particles interact with the ambient medium. These observations, which provide more or less direct information on the topology and dynamics of the magnetic structures in which particles are accelerated and propagate, are discussed in the framework of the statistical flare scenario.     

Review of unsteady transonic aerodynamics: Theory and applications

Unsteady transonic flow theory is reviewed and classical results from the nonlinear asymptotic theory are combined with new results from computational fluid dynamics. The emphasis is on applications to the field of aeroelasticity and on clarifying the limitations of linearized theories in problems involving mixed subsonic-supersonic flows. The inherent differences between nonlinear transonic aerodynamics and linear subsonic and supersonic aerodynamics are considered from a theoretical and computational standpoint, and the practical implications of these differences in formulating suitable aerodynamic models for aeroelastic stability calculations are discussed. Transonic similarity principles are reviewed and their relevance in understanding flutter, divergence, and control reversal phenomena of transonic aircraft is illustrated through practical examples.     

EUV spectroscopy as a plasma diagnostic

The EUV wavelength regions is rich in emission lines from the transition region and the corona. Spectroscopic techniques have been used extensively to determine the physical conditions in the solar atmosphere for such diverse phenomena as coronal holes, active regions, sunspots, flares, etc. The diagnostics and dynamics of plasmas, both homogeneous and inhomogeneous plasmas, are reviewed. The future projects such as the CDS and SUMER instruments on SOHO have been discussed as they cover EUV wavelength region and will provide a wealth of observational data with excellent spatial, spectral, and temporal resolution.     

变化风场中无人机的动力学建模及飞行特性分析

研究了变化风场中无人机的动力学建模与飞行特性问题.给出了大气扰动的Von Kaman模型,推导出变化风场中无人机的六自由度非线性动力学模型,最后基于上述模型进行数值计算,分析了变化风场中无人机的飞行特性.结果表明,该模型能准确地描述无人机的动力学和运动学规律;大气扰动下,各运动参数均产生不同幅度的振荡;同一频谱的扰动在...     

9. The venus ionosphere and solar wind interaction

The current state of knowledge of the chemistry, dynamics and energetics of the upper atmosphere and ionosphere of Venus is reviewed together with the nature of the solar wind-Venus interaction. Because of the weak, though perhaps not negligible, intrinsic magnetic field of Venus, the mutual effects between these regions are probably strong and unique in the solar system. The ability of the Pioneer Venus Bus and Orbiter experiments to provide the required data to answer the questions outstanding is discussed in detail.     

Ionospheric Storms — A Review

In this paper, our current understanding and recent advances in the study of ionospheric storms is reviewed, with emphasis on the F2-region. Ionospheric storms represent an extreme form of space weather with important effects on ground- and space-based technological systems. These phenomena are driven by highly variable solar and magnetospheric energy inputs to the Earth's upper atmosphere, which continue to provide a major difficulty for attempts now being made to simulate the detailed storm response of the coupled neutral and ionized upper atmospheric constituents using increasingly sophisticated global first principle physical models. Several major programs for coordinated theoretical and experimental study of these storms are now underway. These are beginning to bear fruit in the form of improved physical understanding and prediction of ionospheric storm effects at high, middle, and low latitude. This revised version was published online in June 2006 with corrections to the Cover Date.     

Cosmic Ray Induced Ion Production in the Atmosphere

An overview is presented of basic results and recent developments in the field of cosmic ray induced ionisation in the atmosphere, including a general introduction to the mechanism of cosmic ray induced ion production. We summarize the results of direct and indirect measurements of the atmospheric ionisation with special emphasis to long-term variations. Models describing the ion production in the atmosphere are also overviewed together with detailed results of the full Monte-Carlo simulation of a cosmic ray induced atmospheric cascade. Finally, conclusions are drawn on the present state and further perspectives of measuring and modeling cosmic ray induced ionisation in the terrestrial atmosphere.     

The structure of the Venus ionosphere

Our current knowledge of the spatial structure of the Venus ionosphere and its temporal behavior is reviewed, with emphasis on the more recent Pioneer Venus measurements and analysis not covered in earlier reviews. We will stress the ionosphere structure, since other papers in this issue deal with its dynamics, and its magnetic properties. We also discuss some of the limitations that the orbit has placed on the spatial and temporal coverage of the ionosphere. For the benefit of future users of the data some of the factors which affect the measurement accuracies are discussed in an Appendix.Currently at Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109, U.S.A.     

Neutron measurements in space

The experimental measurements of the neutron flux and energy spectrum in space since 1964 are reviewed and related to the theoretical predictions. A discussion of the neutron sources is presented. The difficulties associated with neutron measurements of both the atmospheric neutron leakage flux and solar neutrons are included. Particular emphasis is placed upon the neutron leakage flux and energy measurements at energies greater than about 1 MeV. The possibilities of CRAND as a source for the energetic trapped protons are discussed in light of recent measurements of the 10–100 MeV neutron flux. The current status of the solar neutron flux observations is also presented.The primary purposes of neutron measurements in space have been to determine the neutron leakage flux from the atmosphere of the Earth and the solar neutron flux. As a consequence of the inefficient methods for neutron detection and the difficulties of conducting the measurements in the presence of the galactic and solar cosmic-ray backgrounds, the experimental results are very conflicting. It is the purpose of this review to interpret and discuss recent neutron measurements. In order to understand these results the theoretical predictions of the neutron fluxes and energy spectra from possible neutron sources will be briefly presented. Since comparisons of the different neutron measurements depend critically upon the experimental techniques, we will briefly discuss neutron detection methods applicable to space measurements. The emphasis will be upon measurements since 1964 made outside the Earth's atmosphere, but considerable reference will be made to high energy neutron experiments conducted within the Earth's atmosphere at < 10g cm^-2 altitude. A review of earlier neutron measurements of terrestrial and solar neutrons has been made by Haymes (1965).     

防弹陶瓷的研究现状与发展趋势

综述了防弹陶瓷的研究现状,介绍了两种典型的防弹陶瓷。对于Al2O3防弹陶瓷着重于复相结构的分析;对于B4C着重于烧结工艺及陶瓷性能方面的概述。并对防弹陶瓷今后的发展进行了预测,列举了几种较新的防弹陶瓷材料并提出了将纳米复相陶瓷用于防弹方面的设想。     

The heating of the solar corona

In this paper a discussion is given of the present state of the theory of the heating of the solar corona by shock waves. Arguments are presented why the main contribution to the mechanical energy flux is of acoustic origin, while estimates for the amount of acoustic energy generated in the convection zone as well as the deviations from isotropy are given. During propagation through the atmosphere acoustic waves develop into shock waves after a distance of a few scale heights in the chromosphere. The heating of the outer layers by dissipation of shock waves is found to be sufficient to account for the observed radiative and corpuscular energy losses.Much emphasis is laid on the competitive role played by the four fundamental processes of energy transfer: mechanical heating, radiation, heat conduction and convection of energy in establishing the equilibrium structure of the corona. The atmosphere may be divided in several regions according to the predominance of one of the energy processes mentioned above.The physical properties of the chromosphere and the solar wind are discussed only where they are intimately connected with the problem of the heating of the corona.The most important aspects of the influence of a magnetic field on the structure and the heating of the corona in magnetically active regions are briefly mentioned. Special attention is paid to the strong channelling of heat flow along the field lines and its consequences for the structure and dynamics of the chromosphere-corona transition layer.     

THE INFLUENCE OF THE LOCAL INTERSTELLAR MEDIUM ON THE SOLAR WIND DYNAMICS IN THE INNER HELIOSPHERE

The consequences of the interaction between the solar wind and the local interstellar medium for the wind region enclosed by the heliospheric shock are reviewed. After identifying the principal mechanisms to influence the dynamics of the solar wind, an approach allowing the simultaneous incorporation of neutral atoms, pick-up ions, cosmic rays and energetic electrons into a multifluid model of the expanding wind plasma is outlined. The effects of these particle species are discussed in detail, with special emphasis on the electron component which behaves more like a quasi-static hot gas rather than an expanding fluid. This electron gas is effectively trapped within a three-dimensional trough of a circumsolar electric potential whose outer fringes are possibly determined by the density distribution of anomalous cosmic rays. The electrons are proven to be a globally structered component of great importance for the solar wind momentum flow contributing to a triggering of the solar wind dynamics by asymmetric interstellar boundary conditions. Finally, the consequences for the relative motion of the Sun and the local interstellar medium as well as for the solar system as a whole are described.     

Solar mass flow in fine-scale structures

Observations of transient and steady velocities at chromospheric, transition region and coronal temperatures in the quiet Sun and coronal holes are reviewed. The relevance of fine-scale structures in governing the mass balance of the solar atmosphere is stressed. At present, a coherent picture of these mass flows does not exist. However, the current observational base of transition region and coronal velocity information is limited but should greatly improve with measurements from the SOHO satellite.