Composition of Light Solar Wind Noble Gases in the Bulk Metallic Glass flown on the Genesis Mission

We discuss data of light noble gases from the solar wind implanted into a metallic glass target flown on the Genesis mission. Helium and neon isotopic compositions of the bulk solar wind trapped in this target during 887 days of exposure to the solar wind do not deviate significantly from the values in foils of the Apollo Solar Wind Composition experiments, which have been exposed for hours to days. In general, the depth profile of the Ne isotopic composition is similar to those often found in lunar soils, and essentially very well reproduced by ion-implantation modelling, adopting the measured velocity distribution of solar particles during the Genesis exposure and assuming a uniform isotopic composition of solar wind neon. The results confirm that contributions from high-energy particles to the solar wind fluence are negligible, which is consistent with in-situ observations. This makes the enigmatic “SEP-Ne” component, apparently present in lunar grains at relatively large depth, obsolete. ²⁰Ne/ ²²Ne ratios in gas trapped very near the metallic glass surface are up to 10% higher than predicted by ion implantation simulations. We attribute this superficially trapped gas to very low-speed, current-sheet-related solar wind, which has been fractionated in the corona due to inefficient Coulomb drag.     

Doo-Sabin细分算法的实现

在细分曲面造型中，对Doo-Sabin曲面为代表的细分曲面的研究，已成为近几年来图形学领域最重要的研究课题，但已有文献在细分算法的实现方面缺乏具体操作过程，不便于工程应用。本文分析了Doo-Sabin细分算法的数据结构特点，研究了细分算法的具体实现过程，对连接规律进行了总结，实现了Doo-Sabin细分算法的二次曲面细分，为各种相关文献缺乏具体操作过程作了补充。     

浅析Ackermann函数

利用递归函数显式化的一种新方法,给出了Akermann函数显式表示法,从而确定Akermann函数算法的时间复杂度为2幂函数级.     

3He-Rich Solar Energetic Particle Events

³He-rich solar energetic particle (SEP) events show huge enrichments of ³He and association with kilovolt electrons and Type-III radio bursts. Observations from a new generation of high resolution instruments launched on the Wind, ACE, Yohkoh, SOHO, TRACE, and RHESSI spacecraft have revealed many new properties of these events: the particle energy spectra are found to be either power-law or curved in shape, with the ³He spectrum often being distinctly different from other species. Ultra-heavy nuclei up to >200 amu are found to be routinely present at average enrichments of >200 times solar-system abundances. The high ionization states previously observed near ∼1 MeV/nucleon have been found to decrease towards normal solar coronal values in these events. The source regions have been identified for many events, and are associated with X-ray jets and EUV flares that are associated with magnetic reconnection sites near active regions. This paper reviews the current experimental picture and theoretical models, with emphasis on the new insights found in the last few years.     

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.     

Current dissipation within the chromosphere-corona transition

Studies of sporadic outbursts, ranging from flares to nano-flares, invariably endow the solar corona with steady plasma conditions, prior to seeking a current-flow (or the associated magnetic structure) which induces instability. Such an approach does not incorporate a crucial feature of the natural configuration, namely, that the material is of chromospheric origin, and only resides at coronal altitudes for as long as it can acquire adequate energy. There is clearly a feedback loop involved, which allows plasma to moderate the transfer of energy from the field while making use of this heat to permeate coronal altitudes. An examination of the whole procedure is necessary if the location and threshold-conditions for the energy-conversion mechanism are to be identified.A critical step in the feedback procedure mentioned involves the supply line which links the corona to the chromosphere. Because the solar atmosphere has such large vertical dimensions, even a modest change in average temperature and/or density can place heavy demands on this artery: the problem is that a conventional conduction-dominated transition layer cannot readily accommodate a rapid increase in current-density or plasma-flow. (Restructuring of the temperature gradient, to provide the carriers with extra heat, is a very slow process.) A transition layer of this type is unable to endure for long at the base of a sporadically-heated atmosphere in any case, since it becomes the target for plasma falling in the gravitational field during each intermediate cooling phase. As a result, the gap between the chromosphere and corona is more abrupt than is usually considered, endowing the region with thermo-electric characteristics which allow energy to be extracted when modest current-densities arise. Energy-conversion at this region fulfills two rôles: it supplies at least part of the heat required by the overlying corona, and maintains contact between the chromosphere and corona via non-thermal transport processes.     

多媒体智能数据库系统MIDS／BUAA

ＩＤＢ（智能数据库）思想的提出，预示着人类的信息处理即将步入一个崭新的时代．ＩＤＢ将计算机科学中近年来日趋发展成熟的五大主要技术，ΟΟ（面向对象）技术、ＤＢ（数据库）技术、ＡＩ（人工智能）、Ｈｙｐｅｒｔｅｘｔ／Ｈｙｐｅｒｍｅｄｉａ（超文本／超媒体）和正文数据库与联机信息检索技术，集成为一体．其中ΟΟ、ＡＩ和ＤＢ是ＩＤＢ中的三大支柱技术．本文论述ＭＩＤＳ／ＢＵＡＡ数据模型（Ｄａｔａｍｏｄｅｌｉｎｇ）的哲学，并介绍ＭＩＤＳ／ＢＵＡＡ系统的设计思想、动机、核心数据模型，系统的功能构成和它的Ｃｌｉｅｎｔ／Ｓｅｒｖｅｒ体系结构．     

飞机起落架上位锁机构可靠性分析

对机构系统可靠性分析的典型方法进行了阐述，并以某国产民机的主起落架上位锁系统为例进行了功能可靠性性定量分析，此工程分析方法也适用于同类问题。     

武装直升飞机雷达散射截面的估算方法

讨论了在预告不知道武装直升飞机详细外形数据的情况下，根据三视图及少量外形数据，对其外形进行拟合，对雷达散射截面进行估算的方法，并对一武装直升飞机进行了理论计算和实验测试，结果吻合较好。     

一种求非线性规划全局最小解的算法

在评述了近２０年来发展的全局最优化方法之后，提出了一种求解全局最优化问题的算法，即从一个求得的局部最小解点出发，去解一个最大化问题，这个最大化问题是构造一个辅助函数去寻求一个更好的局部最优解，这样就产生一个局部最小解序列，得后得到全局最小解，另外还有了全局收敛性定理，也给出了数值例子。