Interplanetary Physics Research in China During 2004 - 2005

This brief report summarized the latest advances of the interplanetary physics research in China during the period of 2004-2005, made independently by Chinese space physicists and through international collaboration. The report covers all aspects of the interplanetary physics, including theoretical studies, numerical simulation and data analysis.     

Acceleration of Solar-Energetic Particles by Shocks

Our current understanding of the acceleration of solar-energetic particles is reviewed. The emphasis in this paper is on analytic theory and numerical modeling of the physics of diffusive shock acceleration. This mechanism naturally produces an energy spectrum that is a power law over a given energy interval that is below a characteristic energy where the spectrum has a break, or a rollover. This power law is a common feature in the observations of all types of solar-energetic particles, and not necessarily just those associated with shock waves (e.g. events associated with impulsive solar flares which are often described in terms of resonant stochastic acceleration). Moreover, the spectral index is observed to have remarkably little variability from one event to the next (about 50%). Any successful acceleration mechanism must be able to produce this feature naturally and have a resulting power-law index that does not depend on physical parameters that are expected to vary considerably. Currently, only diffusive shock acceleration does this.     

Dust Environment Modelling of Comet 67P/Churyumov-Gerasimenko

Dust is an important constituent of cometary emission; its analysis is one of the major objectives of ESA’s Rosetta mission to comet 67P/Churyumov-Gerasimenko (C–G). Several instruments aboard Rosetta are dedicated to studying various aspects of dust in the cometary coma, all of which require a certain level of exposure to dust to achieve their goals. At the same time, impacts of dust particles can constitute a hazard to the spacecraft. To conciliate the demands of dust collection instruments and spacecraft safety, it is desirable to assess the dust environment in the coma even before the arrival of Rosetta. We describe the present status of modelling the dust coma of 67P/C–G and predict the speed and flux of dust in the coma, the dust fluence on a spacecraft along sample trajectories, and the radiation environment in the coma. The model will need to be refined when more details of the coma are revealed by observations. An overview of astronomical observations of 67P/C–G is given, because model parameters are derived from this data if possible. For quantities not yet measured for 67P/C–G, we use values obtained for other comets, e.g. concerning the optical and compositional properties of the dust grains. One of the most important and most controversial parameters is the dust mass distribution. We summarise the mass distribution functions derived from the in-situ measurements at comet 1P/Halley in 1986. For 67P/C–G, constraining the mass distribution is currently only possible by the analysis of astronomical images. We find that both the dust mass distribution and the time dependence of the dust production rate of 67P/C–G are those of a fairly typical comet.     

Ptolemy – an Instrument to Measure Stable Isotopic Ratios of Key Volatiles on a Cometary Nucleus

A fundamental goal of cometary studies is to determine the exact relationship between these bodies and the Solar System – the question(s) can be summarised as follows: did comets originate during the same events that spawned the Sun and planets, are they more primitive bodies that record a pre-solar history, or are they interstellar materials collected in relatively more recent times? Now, whatever the origin of comets, it is entirely possible that they could, in part, contain interstellar or pre-solar components – indeed, it seems rather likely in light of the fact that primitive meteorites contain such entities. These particular components are likely to be refractory (dust, macromolecular organic complexes, etc.). Of more relevance to the issues above are the volatile constituents, which make up the bulk of a comet's mass. Since these materials, by their very nature, volatilise during perihelion passage of a comet they can, in some instances, be detected and measured spectroscopically. Perhaps the most useful species for isotopic investigations are C₂, HCN and CN. Unfortunately, spectroscopic measurements can only currently be made with accuracies of ±10 to ±20%. As such it is very often not practical to conclude anything further than the fact that isotopic measurements are compatible with ‘`solar’' values, which tends to imply an origin from the margins of the solar accretion disk. But there is another problem with the spectroscopic measurements – since these are made on gaseous species in the coma (and relatively minor species at that) it is impossible to be certain that these represent the true nuclear values. In other words, if the processes of sublimation, active jetting, and photochemistry in the coma impart isotopic fractionation, the spectroscopic measurements could give a false impression of the true isotope ratios. What is required is an experiment capable of measuring isotopic ratios at the very surface of a comet. Herein we describe the Ptolemy instrument, which is included on the Philae lander as part of the Rosetta mission to 67P/Churyumov-Gerasimenko. The major objective of Ptolemy is a detailed appraisal of the nature and isotopic compositions of all materials present at the surface of a comet.     

Internet环境下的虚拟企业客户关系管理系统

Internet的发展，为虚拟企业客户关系管理的计算机网络化提供了技术支持，利用Internet技术将虚拟企业范围内的各合作企业的客户关系管理进行整合，在Internet平台上建立虚拟企业各合作企业共同的客户关系管理系统，可以提高虚拟企业的客户关系管理的能力。文章从分析客户关系管理和虚拟企业入手，提出了构建虚拟企业客户关系管理系统的设想。     

航空壳体类零件虚拟加工仿真的研究

以航空壳体类零件为研究对象,分析该类零件的结构特点,利用UG和VERICUT的功能,形成了一套航空壳体类零件虚拟加工仿真方法。     

灰色预测在MCMQC中的应用

分析了大规模定制生产中的质量控制中灰色预测算法的简单快速的优点和精度不高的缺点,及造成这一现象的本质原因,并提出了改进大规模定制生产灰色质量控制的思路。     

航空维修训练模拟系统关键技术研究

针对当前模拟训练在我军航空维修领域应用还不成熟,模拟系统仿真逼真度和可信度不高的问题,通过分析航空维修训练模拟系统国内外发展现状,并通过对我国相关科研机构进行实地调研考察,总结出了目前航空维修领域较典型的几种模拟系统构建方式,给出了各种构建方式的优缺点及各自的典型代表,归纳出了航空维修训练模拟系统实现的关键技术途径以及每种技术途径研究的重点、难点,给出了我军航空维修训练模拟系统未来应重点努力发展的方向.     

Experiments on film cooling with sonic injection into a supersonic flow

Film cooling experiments with sonic injection were conducted to investigate the effects of the number of the injection holes, the mass flow ratio, and the hole spacing on the film cooling effectiveness. The mainstream was obtained by the hydrogen-oxygen combustion, entering the experimental section at a Mach number of 2.0. The nitrogen with ambient temperature was injected into the experimental section at a sonic speed. The measured mainstream recovery temperature was approximately 910K. The mass flow ratio was regulated by varying the nitrogen injection pressure. The experimental results show that for the investigated cooling surface, the cooling effectiveness increases with the increase in the number of the injection holes with other parameters held constant. For a fixed cooling configuration, the cooling effectiveness increases with the increase in the mass flow ratio. Different from the subsonic film cooling, the optimal mass flow ratio is not observed. When the hole spacing is less than 4, no obvious difference is observed on the cooling effectiveness and lateral uniformity. With the mass flow ratio increasing further, this difference becomes much smaller. The shock wave also has an effect on the cooling effectiveness. Downstream the incident point of the shock wave, the cooling effectiveness is lower than that in the case without the shock wave.     

Solar extreme events 2005–2006: Effects on near-Earth space systems and interplanetary systems

Extreme events are defined as those events in which the characteristics (e.g. field strength, speed, intensity of radiation, energies) of the associated phenomena (e.g. solar flares, coronal mass ejections, solar proton events) are some orders of magnitude larger than in other events. Such strong events commonly occur about two years before and after sunspot maximum and some strong events occur as well in the declining phase before the solar activity minimum [Bothmer V., Zhukov A. The 11 Sun as the prime source of space weather, in: Bothmer, V., Daglis, I. (Eds.), Space Weather: Physics and Effects, Springer Praxis Books, 12 pp. 438, 2007]. In the first part of the paper the characteristics of the Jan. 2005 and Dec. 2006 events are given. This is followed by a presentation of the effects that were encountered on technological systems and also addresses the issue of what could have occurred on biological systems during such events. The second part of the paper deals with how one should go about analyzing solar extreme events - as part of the global distribution of all events or as ”outliers” with their own special characteristics.