The Cool Interstellar Medium

Infrared spectroscopy and photometry with ISO covering most of the emission range of the interstellar medium has led to important progress in the understanding of the physics and chemistry of the gas, the nature and evolution of the dust grains and also the coupling between the gas and the grains. We review here the ISO results on the cool and low-excitation regions of the interstellar medium, where T _gas≲ 500 K, n _H∼ 100–10⁵ cm⁻³ and the electron density is a few 10⁻⁴. JEL codes: D24, L60, 047 Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands, and the United Kingdom), and with the participation of ISAS and NASA.     

原子谱线参数的辨识方法

在一种原子谱线参数测量的辨识方法基础上编制了一套原子港线参数辨识的标准软件。用此软件对纯氩和氩、氮混合非平衡电弧等离子体射流的原子谱线进行了处理，获得了射流的电子温度、气体平动温度、电子和原子数密度。状态诊断表明；实验条件下的等离子体射流除中心点为ＬＴＥ外非平衡效应是非常显著的。     

Interplanetary scintillation observations of the high-latitude solar wind

Until the ULYSSES spacecraft reached the polar regions of the solar wind, the only high-latitude measurements available were from indirect techniques. The most productive observations in regions of the solar wind between 5R and 200R have been the family of radio scattering techniques loosely referred to as Interplanetary Scintillation (IPS) (Coles, 1978). Useful observations can be obtained using a variety of radio sources, for example spacecraft beacons, planetary radar echoes and compact cosmic sources (quasars, active galactic nuclei, pulsars, galactic masers, etc.). However for measurement of the high-latitude solar wind cosmic sources provide the widest coverage and this review will be confined to such observations. IPS observations played a very important role in establishing that polar coronal holes (first observed in soft x-ray emission) were sources of fast solar wind streams which occasionally extend down to the equatorial region and are observed by spacecraft. Here I will review the IPS technique and show the variation of both the velocity and the turbulence level with latitude over the last solar cycle. I will also outline recent work and discuss comparisons that we hope to make between IPS and ULYSSES observations.     

跨声轴流压气机等离子体控制实验

为了能有效地拓宽压气机的失稳裕度,在一台跨声轴流压气机上进行了基于介质阻挡放电（DBD）等离子体激励扩稳的实验研究.实验中分别选取了正弦交流电源和纳秒脉冲电源提供激励,并在跨声压气机40%设计转速和65%设计转速下对其扩稳效果和效率进行了对比分析.结果表明:在40%设计转速时,正弦交流电源和纳秒脉冲电源均能有效拓宽压气机流量范围,其中正弦交流电源激励方式能够使压气机综合失速裕度改善（SMI）达到15.33%.在65%设计转速时,两种激励方式的扩稳效果明显减弱,此时纳秒脉冲电源激励方式的扩稳效果更好.在压气机效率方面,纳秒脉冲电源对压气机设计点的效率影响更小,在40%设计转速时甚至能略微提升其设计点效率.实验结果表明,合理地选择激励方式有助于提高等离子体激励的扩稳效果,为实际压气机中基于介质阻挡放电等离子体激励扩稳措施的设计提供参考.      

二维实验固体燃料冲压发动机冷流数值分析

本文在冷流情况下，对已初步完成设计的二维实验ＳＦＲＪ建立了数学模型并进行了数值解，得出了一些有用的结构，对ＳＦＲＪ的精确设计和实验数据提供了有用的理论研究基础。     

X-ray radiation from accreting, magnetized neutron stars

A review is given of recent developments in the theory of emission from a magnetized plasma for accreting neutron star conditions. Some observational data on X-ray pulsars are discussed, and present problems are indicated.     

Preparation of bimodal grain size 7075 aviation aluminum alloys and their corrosion properties

The bimodal grain size metals show improved strength and ductility compared to traditional metals; however, their corrosion properties are unknown. In order to evaluate the corrosion properties of these metals, the bimodal grain size 7075 aviation aluminum alloys containing different ratios of coarse(100 μm in diameter) and fine(10 μm in diameter) grains were prepared by spark plasma sintering(SPS). The effects of grain size as well as the mixture degree of coarse and fine grains on general corrosion were estimated by immersion tests, electrochemical measurements and complementary techniques such as scanning electron microscope(SEM) and transmission electron microscope-energy disperse spectroscopy(TEM-EDS). The results show that, compared to fine grains, the coarse grains have a faster dissolution rate in acidic NaCl solution due to the bigger size,higher alloying elements content and larger area fraction of second phases in them. In coarse grains,the hydrogen ions have a faster reduction rate on cathodic second phases, therefore promoting the corrosion propagation. The mixture of coarse and fine grains also increases the electrochemical heterogeneity of alloys in micro-scale, and thus the increased mixture degree of these grains in metal matrix accelerates the corrosion rate of alloys in acidic NaCl solution.     

Kinetic theory of the current sheath. II. Effect of polarization on the stability of a current sheath

A procedure for investigating the stability of a current sheath, taking into account the effect of plasma polarization, is offered. The kinetic equation with a self-consistent electromagnetic field for perturbation of the distribution function is solved. On the basis of this solution, the tensor of dielectric permeability for a non-electroneutral current sheath plasma is calculated, and the dispersion equation for the study of possible instability modes of this current sheath is obtained. The instability of the current sheath of the magnetospheric tail with respect to tearing perturbations, and the influence of the effect of plasma polarization on the development of tearing instability, are investigated.     

Study of the 28 October 2003 and 20 January 2005 solar flares by means of 2.223 MeV gamma-emission line

By the data on intensity-time profiles of the neutron capture line of 2.223 MeV we have studied some characteristics of two solar flares, 28 October 2003 and 20 January 2005 (INTEGRAL and CORONAS-F observations, respectively). The SINP code was applied making allowance for the main processes of neutron interactions and deceleration in the solar plasma, character of neutron source, losses of neutrons and density model of the solar atmosphere. Comparison of the computed time profiles of 2.223 MeV line with observed ones for the flare of 28 October 2003 confirms the results obtained earlier for three other flares. Namely, the effect of density enhancement (EDE) in the sub-flare region, as well as the variations (hardening) of accelerated particle spectrum in the course of the event have been confirmed. The usual modeling procedure by the SINP code, however, seems to be inapplicable to the event of 20 January 2005. Possible causes of density enhancements during some flares and peculiarities of the 20 January 2005 flare are discussed.     

Effects of Hybrid Voltages on Oxide Formation on 6061 Al-alloys During Plasma Electrolytic Oxidation

Plasma electrolytic oxidation (PEO) is carried out on 6061 Al-alloys in a weak alkaline electrolyte containing NaOH, Na₂SiO₃ and NaCl. Centered on the correlation of composition and structure, analyses by means of X-ray diffration (XRD), scanning electron microscope (SEM) and energy dispersive spectrometry (EDS) are conducted on the specimens, which have been PEO-treated under hybrid voltages of different direct current (DC) values (140-280 V) with constant alternate current (AC) amplitude (200 V). Attention is paid to the composition, properties and growth mechanism of oxide layers formed with hybrid voltages. Moreover, the main effects of DC value are discussed. Ceramic layers with a double-layer structure which combines hard outer and soft inner layers are found to be consist of α-Al₂O₃, γ-Al₂O₃ and mullite. With the DC values increasing, the growth of the ceramic layers tends to have increasingly obvious three-stage feature.