改性酚醛基复合材料的摩擦系数研究

研制了一种准高速列车盘形制动装置用混杂纤维增强改性酚醛基复合材料,在1:1惯性力矩试验台上研究了在干摩擦条件下以不同制动初速度、不同闸片压力实施惯性制动时的摩擦特性,利用扫描电镜对试验后的材料摩擦表面形貌进行观察。试验结果表明:瞬时摩擦系数随瞬时速度的变化与制动初速度有关,高接触压力下的摩擦系数低于低接触压力下的摩擦系数;在于摩擦、一次停车惯性制动条件下,临界使用条件是接触压力为0.82MPa,制动初速度为27.3m/s。摩擦表面生成摩擦膜是摩擦系数变化的主要原因。     

真空热爆加压法制备高颗粒含量TiCp/2024复合材料

采用真空热爆加压法（简称ＶＴＥＰ）工艺制备了高粒子含量ＴｉＣｐ／２０２４复合材料。通过数据采集器记录了不同铝含量时热爆反应的时间－－温度曲线;通过ＸＲＤ分析了ＴｉＣｐ／２０２４复合材料的相组成;用ＳＥＭ和ＴＥＭ观察了ＴｉＣｐ／２０２４复合材料的显微组织、微观结构和断口形貌。结果表明：ＶＴＥＰ工艺可以获得颗粒细小圆整、分布均匀、致密的高颗粒含量ＴｉＣｐ／２０２４复合材料。     

大气成分探测红外光谱仪系统指标分析

由温室气体引起的全球气候变化和环境污染已经受到全世界的广泛关注。进行大气成分探测,对于更好地了解温室效应产生的细节、大气分子的光化学性质对臭氧层的影响以及大气污染机制都具有重要意义。由于大气成分种类较多,其红外吸收光谱密集且复杂,因此大气成分探测仪器需要有较高的光谱分辨能力和信噪比。文章进行了大气成分探测的总体指标需求分析,并据此确定了大气成分探测红外光谱仪的主要技术指标。为了满足指标要求,该光谱仪采用傅里叶变换红外光谱仪的总体方案。通过仪器性能影响因素分析和系统优化,使得该仪器的最终设计结果满足指标要求。     

基于云蚁群算法的高效节能氩弧焊工艺参数优化研究

为在氩弧焊加工过程中提升效率的同时降低能耗,研究了一种氩弧焊高效节能工艺参数的多目标优化模型及算法。首先确定了以焊接速度及焊接电流为优化变量,在综合考虑焊接设备、工件特性、操作方法及焊接质量等约束的前提下,建立了以最小电能消耗以及最短加工时长为优化目标的多目标工艺参数优化模型;提出一种基于云模型的蚁群算法(CBACO)以对所构建的优化模型进行求解,其中包含一种适当的编码方式、一种局部与全局相结合的探索策略、一种基于云模型的变异因子、传统的单点交叉因子、单形交叉因子以及适当的选择策略;通过一个针对某航空器油箱的焊接实例,对所提出的优化模型及算法的实用性进行了验证,结果表明优化参数可在保证加工质量的前提下有效地节省时间60.41%~69.05%,节省电能34.88%~46.30%。     

METHIS: Mercury thermal infrared spectrometer

The BepiColombo mission to Mercury is devoted to the thorough exploration of Mercury and its environment, with the aim to understand the processes of planetary formation and evolution in the hottest part of the protoplanetary nebula. This mission represents an unique opportunity for the European community to extend the understanding of the Solar Nebula evolution from its outer edge – ideally represented by comets – to its inner and warmer edge. Obviously this exploration asks for a detailed knowledge of the main constituents of the matter present in the different Solar System areas. Spectroscopy is a powerful tool to acquire this knowledge. We have participated with a large consortium of European researchers to the development of the Rosetta imaging spectrometer. We propose here to use our experience to develop a newly designed spectrometer to investigate the mineralogical composition of the Mercurial surface. Given the particular thermodynamical situation of the Mercurial surface, we have developed a concept that combines a medium IR low spectral resolution imager with a moderate spectral resolution NIR point spectrometer. The main goal of METHIS is to provide the mineralogical characterisation of the surface with sufficient spectral resolution in a scientifically diagnostic spectral range.     

立体构成中的能力培育、创造力育成

立体构成学习不再是简单的技能培训，也不是模仿性的学习，重点在于创造意识、创造能力的培养。本文阐述了立体构成中能力的培育、创造力的育成的新观点、新认识。     

Solar Energetic Particle Charge States: An Overview

The ionic charge distributions of solar energetic particles (SEP) as observed in interplanetary space provide fundamental information about the origin of these particles, and the acceleration and propagation processes at the Sun and in interplanetary space. In this paper we review the measurements of ionic charge states of energetic particles in interplanetary space and discuss their implication for our understanding of SEP sources, and acceleration and propagation processes.     

The Lower Solar Atmosphere Rapporteur Paper II

This “rapporteur” report discusses the solar photosphere and low chromosphere in the context of chemical composition studies. The highly dynamical nature of the photosphere does not seem to jeopardize precise determination of solar abundances in classical fashion. It is still an open question how the highly dynamical nature of the low chromosphere contributes to first ionization potential (FIP) fractionation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Remote Observations of the Composition of Cometary Volatiles

The volatile species released in the coma are an important clue to the composition of the cometary nucleus ices. Their identification and the measurement of their abundances is possible by remote sensing. Considerable progress has been made recently using radio and infrared spectroscopy, especially with the observations of the two exceptional comets C/1996 B2 (Hyakutake) and C/1995 O1 (Hale-Bopp).) 24 molecules likely to be parent molecules outgassed from the nucleus have now been identified. Significant upper limits exist for many other species, and the presence of unidentified lines suggests that further species are to be identified. In addition, isotopic varieties have been observed for hydrogen, carbon, nitrogen and sulphur. We will review these results with a special emphasis on the reliability of the identifications and of the molecular production rate determinations. A critical point is to assess whether a given species is a genuine parent molecule outgassed from nuclear ices, or is a secondary product coming from grains or from gas-phase photochemistry. Ground-based spectral imaging, such as radio interferometry, may help resolving this problem. This revised version was published online in June 2006 with corrections to the Cover Date.     

Inner radiation belt source of helium and heavy hydrogen isotopes

Nuclear interactions between inner zone protons and atoms in the upper atmosphere provide the main source of energetic H and He isotopes nuclei in the radiation belt. This paper reports on the specified calculations of these isotope intensities using various inner zone proton intensity models (AP-8 and SAMPEX/PET PSB97), the atmosphere drift-averaged composition and density model MSIS-90, and cross-sections of the interaction processes from the GNASH nuclear model code. To calculate drift-averaged densities and energy losses of secondaries, the particles were tracked in the geomagnetic field (modelled through IGRF-95) by integrating numerically the equation of the motion. The calculations take into account the kinematics of nuclear interactions along the whole trajectory of trapped proton. The comparison with new data obtained from the experiments on board RESURS-04 and MITA satellites and with data from SAMPEX and CRRES satellites taken during different phases of solar activity shows that the upper atmosphere is a sufficient source for inner zone helium and heavy hydrogen isotopes. The calculation results are energy spectra and angular distributions of light nuclear isotopes in the inner radiation belt that may be used to develop helium inner radiation belt model and to evaluate their contribution to SEU (single event upset) rates.