Calculation of electron velocity with respect to electrical conduction through single-walled carbon nanotubes

Within the context of electronic transport in a single-walled carbon nanotube, electron velocity (Fermi velocity) is calculated by using a particle-in-a-box model and assuming a prototype single-wall tube in which the Fermi velocity is the average value of the electron velocity as a function of the tube radius when all the possible radii are considered. The result of this calculation is compared with the well-known result obtained from a tight-binding approximation and with experimental data.     

散裂中子源漂移管直线加速器功率耦合器的冷测及分析(英)

功率耦合器是中国散裂中子源(CSNS)漂移管直线段(DTL)的关键部件之一,其耦合系数通常通过调节耦合孔尺寸得到,为了确保耦合系数达到设计值,制造了一个冷模进行耦合度的调节。在冷模测量过程中,发现了仅通过改变耦合孔尺寸耦合系数达不到目标值的问题,因此提出了一种与测量结果对比有良好仿真精度的新模型用于分析,并使用该仿真模型分析了PEFP使用的理论及影响耦合度的主要参数。最终耦合度被调节至目标值,正式件的冷测结果也表明其与仿真结果基本相同。     

管间距对翅片管换热器热力性能的影响

分析了翅片管换热器传热及流动阻力性能的影响因素;叙述了场协同理论的基本机理,并与等流速排列方式联系起来加以分析讨论;概述了翅片管换热器研究中管间距对传热及流动阻力影响的国内外研究现状;讨论了不同翅片及基管类型结构尺寸下管间距对换热器传热及流动阻力影响的规律。在此基础上,对管束排列的研究前景进行了展望。     

Cyclization of an Achiral Flipping Panel to Homochiral Tubes Exhibiting Circularly Polarized Luminescence

Macrocyclization of the bendable 2,7-dimethoxythianthrene with methylene linkages afforded a pair of homochiral macrocycles featuring a hex-nut-like geometry. Their structures were fully characterized by NMR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction analysis. Their stable planar chirality facilitates efficient resolution of the pair of enantiomers which could be readily derivatized. Installing phenylethynyl groups on their rims leads to luminescent tubular macrocycles exhibiting circularly polarized luminescence with a large dissymmetry value |g_lum| of 5×10⁻³. Supramolecular binding of electron-deficient guests by the tube results in fluorescence quenching, which proved its potential for the future development of switchable chiroptical systems.     

无限管状区域上次调和函数的边界性质

作者刻画了定义在无限管状区域中次调和函数的边界性质.通过证明一类新型的Phragmen-Lindelof定理,不仅得到了与之相关最大模极限的存在性定理,而且还得到了其具体的表达式.