共查询到20条相似文献,搜索用时 703 毫秒
1.
采用模压成型法制备了不同类型的C/C复合材料,测试了其法向光谱发射率的变化.结果表明,短切碳纤维增强的C/C复合材料,其法向光谱发射率在整个2 500~13 000 nm的测试波段内普遍要高于碳布增强复合材料样品.短切碳纤维结构的相对松散,单位体积内物质的粒子数相对较少,这增加了电磁波的穿透深度,从而使得样品的法向光谱发射率较高,热辐射特性较好.纤维预制体和C/C复合材料样品的法向光谱发射率测试对比可知,两种不同碳材料的微结构差异使得树脂碳的法向光谱发射率优于纤维碳.利用Raman光谱对不同碳物质进行物相分析表明,树脂碳以sp3和sp2杂化态碳原子的混合结构使其内部产生的局域振动模式较多,这也是样品法向光谱发射率较高,热辐射特性较好的原因. 相似文献
2.
Wuosmaa AH Back BB Baker S Brown BA Deibel CM Fallon P Hoffman CR Kay BP Lee HY Lighthall JC Macchiavelli AO Marley ST Pardo RC Rehm KE Schiffer JP Shetty DV Wiedeking M 《Physical review letters》2010,105(13):132501
We have studied the 1?C(d,p)1?C reaction in inverse kinematics using the Helical Orbit Spectrometer at Argonne National Laboratory. Prior studies of electromagnetic-transition rates in 1?C suggested an exotic decoupling of the valence neutrons from the core in that nucleus. Neutron-adding spectroscopic factors give a different probe of the wave functions of the relevant states in 1?C. Shell-model calculations reproduce both the present transfer data and the previously measured transition rates, suggesting that 1?C may be described without invoking very exotic phenomena. 相似文献
3.
4.
5.
利用密度泛涵理论对具有四元环、五元环、六元环、七元环、八元环和九元环等的C60富勒烯及其非经典衍生物:C62,C60,C59和C58共8个笼状分子进行了结构优化和电子结构计算,得到平衡构型下的结合能、HOMO-LUMO能隙、电离能、电子亲和能.对具有缺陷环的富勒烯,还研究了H2分子的贯穿行为,讨论了贯穿势垒与缺陷环尺寸的关系. 相似文献
7.
František Kroupa 《Czechoslovak Journal of Physics》1957,7(3):374-375
8.
C60和C60/C70的激光脱附飞行时间质谱分析 总被引:2,自引:1,他引:1
采用激光脱附并直接测量离子的方法对实验室提取的C_(60)/C_(70)以及进一步分离得到的纯C_(60)进行了飞行时间质谱分析,并讨论了质谱分析过程中实验条件对结果的影响. 相似文献
9.
C60原子团簇与C60团簇固体 总被引:1,自引:0,他引:1
本文回顾了碳的原子团簇研究的历程;综述了C60原子团簇的结构、光吸收,C60团簇固体的结构、方向有序相变及掺杂后的电导、超导电性等物理性质;介绍了样品的制备、分离和掺杂等技术问题;指出了在这一领域开展研究的科学意义. 相似文献
10.
11.
在空气中用253.7nm紫外光照射C60/C70薄膜8h,红外光谱测试表明,C60/C70薄膜产生了光致聚合和氧化。 相似文献
12.
应用密度范函理论(DTF)的B3LYP方法,在6-31G*基组水平上对C1对称C20富勒烯分子及C20-、C202-离子进行了几何结构的全局优化、频率以及自然键轨道分析计算(NBO),然后对三者的几何构型、稳定性、振动光谱等做了分析和比较.研究表明:离子的键长普遍比分子的键长长,C20-离子的稳定性最高.C202-离子的红外峰值较大,C20-离子的拉曼光谱峰值较大,振动光谱可以用来作为区分三者的手段. 相似文献
13.
采用Tersoff-Brenner势的分子动力学方法,研究了双石墨层作用下C60、C240及C60@C240富勒烯分子的压缩力学特性.根据计算结果,讨论了三种分子压缩过程中几何构形、能量、压缩载荷等的变化及其差异.研究表明,压缩过程中,仅C240分子出现了“塌陷“现象,塌陷时,该分子的能量及外载一度下降;相同压缩应变下,C240的体积压缩率以及C60@C240的能量吸收率最大,而C60的体积压缩率及能量吸收率均最小; C60@C240分子的最大承载能力及C240的最大承受变形能力最大,而C60分子的最大承载和最大承受变形能力均最小;在C60@C240分子的压缩中,当应变小于20%时,内笼C60的体积及其能量变化很小;C60与C240之间的范德华尔能在整个压缩C60@C240分子的能量变化中仅仅占有非常小的份额. 相似文献
14.
V. Ya. Basevich A. A. Belyaev V. S. Posvyanskii S. M. Frolov 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(2):161-169
Recently, detailed kinetic mechanisms of the oxidation and combustion of higher hydrocarbons, composed of hundreds of components and thousands of elementary reactions, have been proposed. Despite the undoubtful advantages of such detailed mechanisms, their application to simulations of turbulent combustion and gas dynamic phenomena is difficult because of their complexity. At the same time, to some extent limited, they cannot be considered exhaustive. This work applies previously proposed algorithm for constructing an optimal mechanism of the high- and low-temperature oxidation and combustion of normal paraffin hydrocarbons, which takes into account the main processes determining the reaction rate and the formation of key intermediates and final products. The mechanism has the status of a nonempirical detailed mechanism, since all the constituent elementary reactions have a kinetic substantiation. The mechanism has two specific features: (1) it does not include reactions of so-called double oxygen addition (first to the peroxide radical, and then to its isomeric form), i.e., the first addition turns out to be sufficient; (2) it does not include isomeric compounds and their derivatives as intermediates, since this oxidation pathway is slower than the oxidation of molecules and radicals with normal structure. Application of the algorithm makes it possible to compile a compact mechanism, which is important for modeling chemical processes involving paraffin hydrocarbons C n with large n. Previously, based on this algorithm, compact mechanisms of the oxidation and combustion of propane, n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane have been constructed. In this work, we constructed a nonempirical detailed mechanism of the oxidation and combustion of hydrocarbons from n-undecane to n-hexadecane. The most important feature of the new mechanism is its staged nature, which manifests itself through the emergence of cool and blue flames during low-temperature autoignition. The calculation results are compared with experimental data. 相似文献
15.
测量了C60,C60/C70混合物分别在甲苯和1-甲基萘中的激发谱和荧光光谱,用532nm波长光为激发源。比较了纯C60及C60/C70混合物的荧光特性,对所观察到的发光谱进行了讨论。 相似文献
16.
17.
18.
本文根据G.V.Bochmann在1973年提出的多重出口控制结构思想,在C/C++中分析实现了多重出口循环控制、多重出口函数及其调用。 相似文献
19.
20.
HUGHES C-NITE该系统于1979年开始研制。当时,休斯公司生产的是FACTS,这是一种具有前视红外能力的武器瞄准系统,用来提高Cobra直升机在黑暗、恶劣天气以及战场烟雾(如硝烟)条件下发射、搜索和跟踪TOW导弹的能力,该系统还具有光电抗干... 相似文献