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Dependence of the thermal conductivity on the length of two armchair single-walled carbon nanotubes (SWNTs) is studied by the nonequilibrium molecular dynamics (MD) method with Brenner Ⅱ potential. The thermal conductivities are calculated for (5, 5) and (7, 7) SWNTs with lengths ranging from 22 to 155nm. The results show that the thermal conductivity of SWNTs is sensitive to the length and it does not converge to a finite value when the tube length increases up to 155nm, however it obeys a power law relation. 相似文献
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By employing a multi-walled carbon nanotube (MWCNT) film as the substrate, we obtain Fe tipped carbon nanorods or carbon nanoparticles grown on the outer walls of MWCNTs by combining sputtering deposition of Fe films and rf plasma enhanced chemical vapour deposition at high temperature. Scanning electron microscopy and high-resolution transmission electron microscopy are used to examine the structure of carbon nanorods and carbon nanoparticles. In addition, the formation mechanism is discussed briefly. The electron field emission tests indicate that the turn-on field (at 10μA/cm^2) of the treated MWCNT films decreases from 2.4 V/μm to O. 79 V/μm and the field emission current is relatively stable. The enhanced field enhancement factor, increasing emission densities coming from the grown nanorods and nanoparticles, and H terminated by H plasma a11 are responsible for the enhancement of the field enhancement factor. 相似文献
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A parametrization of ^3He(7,p)2H cross section data at laboratory photon energies between 9 and 150MeV iscarried out with a simple phenomenological function. The differential cross section data are normalized to the total cross-section values which are consistent with the measurement from monochromatic photon beams. The obtained results give a good representation of the experimental points. 相似文献
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在相对论量子场论(QHD)的框架下,得到了相对论线性Vlasov方程.依此计算了球形核16O、40Ca、90Zr及208Pb的巨偶极共振的强度函数分布.结果表明,相对论效应是不可忽视的.计算得到的巨共振中心能量稍高于非相对论线性Vlasov方程给出的对应值,与实验结果比较都有较好的符合.对计算结果作了简要的讨论,发现核子有效质量和平均场自旅轨道耦合力对巨共振能量有重要影想. In the framework of relativistic quantum hadron dynamical (QHD) theory,under semiclassical approximation and taking into vacuum fluctuation, a relativistic Vlasov equation (RVE) has been derived. Using RVE and considering other relativistic effects, we have studied the isovector dipole giant resonances built on ground state in spherical nuclei.The main results show that the resonance energies for each multipole are larger than those obtained from the non-relativistic classical Vlasov approach... 相似文献
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