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21.
Using empirical velocity distributions derived from UVCS and SUMER ultraviolet spectroscopy, we construct theoretical models of anisotropic ion temperatures in the polar solar corona. The primary energy deposition mechanism we investigate is the dissipation of high frequency (10-10000 Hz) ion-cyclotron resonant Alfvén waves which can heat and accelerate ions differently depending on their charge and mass. We find that it is possible to explain the observed high perpendicular temperatures and strong anisotropies with relatively small amplitudes for the resonant waves. There is suggestive evidence for steepening of the Alfvén wave spectrum between the coronal base and the largest heights observed spectroscopically. Because the ion-cyclotron wave dissipation is rapid, even for minor ions like O5+, the observed extended heating seems to demand a constantly replenished population of waves over several solar radii. This indicates that the waves are generated gradually throughout the wind rather than propagated up from the base of the corona. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
22.
通过变温与变激发强度的近红外光致发光研究了用MOCVD方法、生长在GaAs衬底上的Ga0.5In0.5P(GaInP2)外延薄膜的1.17eV发射带的发光特性。1.17eV发光带性质与0.99eV及0.85eV发光带的性质有着明显的差别。1.17eV发光带的机理可用施主-受主对的复合发光来解释,其中施主-受主对系白处在Ga格位上的Si(SiGa)及其最邻近的Ga空位(VGa)所组成,记作SiGa-VGa。考虑到GaInP2中存在着很强的电子-格子耦合作用及其Ⅲ族子格子为部分有序,所以在施主-受主对复合发光中应计及Franck-Condon位移△FC及该对在等效的部分有序势场中的相互作用能Es(DAP)。X—射线衍射实验表明,部分有序结构相当于成分调制,因而可用Kronig-Penney模型来计算Es(DAP)值。这样,我们就导出了施主-受主对复合发光的新的能量表示式。  相似文献   
23.
本文制备了乙酸铈品体,EDTA络合滴定法测定其中铈的含量,利用傅立叶变换红外光谱仪对其进行了红外光谱分析,利用高温综合热分析仪对其进行了热重和差热分析,讨论了乙酸铈晶体在空气气氛中的热分解机理。  相似文献   
24.
We present in this work energy levels, oscillator strengths, radiative decay rates and fine structure collision strengths for the Mg III and Al IV ions. The 11 configurations: (1s2) 2s22p6, 2s22p53l, 2s2p63l, 2s22p54l   (l?n-1l?n-1, where n is the principal quantum number), yielding the lowest 75 levels are used. The collisional data for these two ions are missing in the literature, especially the database CHIANTI, this is the principal motivation behind the present work. Calculations have been performed using the AUTOSTRUCTURE code. AUTOSTRUCTURE treats the scattering problem in the distorted wave approach. Fine structure collision strengths are calculated for a range of electron energies from 10 Ry to 240 Ry. The atomic structure data are compared to available experimental and theoretical results.  相似文献   
25.
采用FLS900型稳态荧光光谱仪对激光持续照射的离体血液进行了荧光检测,得到了血液成分变化及荧光光谱特征随时间衰变的规律。实验结果表明:随着血液离体时间的延长,当受407nm的光激励时,605nm处的荧光峰峰位保持不变仅强度缓慢减弱。但在离体后的14h出现了谱形突变,并在474nm处产生了一个强荧光峰。分析认为,激光对离体血液的衰变有明显的延缓作用,但当激光持续照射一定时间后却导致了细胞的形态改变进而加速了细胞的溶血进程,产生了大量的内源性荧光物质还原烟碱腺嘌呤二核苷酸。研究结果为研究血细胞的活性衰变及细胞功能结构异常等提供了参考。  相似文献   
26.
 本文简要地论述了机械设备故障振动诊断的理论基础,进而基于理论上的分析及作者个人的经验,对旋转机械故障振动诊断的前景作了评述,提出了若干建议。  相似文献   
27.
火星大气层的主要成分为二氧化碳,如果能够利用低温等离子体方法高效分解二氧化碳,使其转化为氧气和一氧化碳加以利用,可以大幅降低航天员生命保障相关载荷长途运输的成本,进一步提高生命保障能力.低温等离子体放电过程中会产生大量活性组分,可以在数百度温度下实现二氧化碳的高效解离,是具有很大潜力的二氧化碳解离与转化方式.设计了一种...  相似文献   
28.
采用磁过滤直流真空阴极弧沉积技术在硅片、不锈钢片基体上制备了类金刚石(DLC)膜。检测结果表明,膜中存在着微米级的大颗粒分布,膜厚为290nm,sp3键的含量为62.23%。所制备的薄膜具有典型的DLC膜Raman光谱特征,耐磨性能优良,膜与基体的结合性能良好。  相似文献   
29.
The diverse populations of icy bodies of the outer Solar System (OSS) give critical information on the composition and structure of the solar nebula and the early phases of planet formation. The two principal repositories of icy bodies are the Kuiper belt or disk, and the Oort Cloud, both of which are the source regions of the comets. Nearly 1000 individual Kuiper belt objects have been discovered; their dynamical distribution is a clue to the early outward migration and gravitational scattering power of Neptune. Pluto is perhaps the largest Kuiper belt object. Pluto is distinguished by its large satellite, a variable atmosphere, and a surface composed of several ices and probable organic solid materials that give it color. Triton is probably a former member of the Kuiper belt population, suggested by its retrograde orbit as a satellite of Neptune. Like Pluto, Triton has a variable atmosphere, compositionally diverse icy surface, and an organic atmospheric haze. Centaur objects appear to come from the Kuiper belt and occupy temporary orbits in the planetary zone; the compositional similarity of one well studied Centaur (5145 Pholus) to comets is notable. New discoveries continue apace, as observational surveys reveal new objects and refined observing techniques yield more physical information about specific bodies.  相似文献   
30.
Observations of pre-main sequence objects (T Tauri, Herbig Ae/Be and FU Orionis stars) obtained with the instrumentation on board the Infrared Space Observatory (ISO) are reviewed. All the observations have been mainly carried out by using the two spectrographs SWS and LWS, adopting their low resolution modes and such data have been used both for lines detection and to reconstruct the spectral energy distributions. Line emission and photometric behaviour of pre-main sequence objects have been analyzed in the framework of the current models, discussing the agreement (or disagreement) with them and trying to derive the questions which should be answered by the forthcoming FIR instrumentation. 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.  相似文献   
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