Modeling double-helix carbon chains inside single-walled carbon nanotubes: Stable structures and XRD analysis

Atomic models are applied to investigate quasi-one-dimensional composites. The study presents the theoretical prediction of stable double-helix carbon chains growing inside single-walled carbon nanotubes as a function of tube radius. Meanwhile, our analysis shows that metastable structures may co-existence with the stable one, for small tubes. The classical molecular dynamics simulation shows that the regular and distorted double-helix C-chains are obtained with the tube's diameter smaller and larger than 13.32 Å, respectively. The temperature plays a minor role in the stable carbon chain structure unit it increases to 2500 K. The geometry optimization and the electronic structural analysis of the obtained optimal structure by the DFT calculation further justify our classical force field analysis. The electronic structure of SWCNTs can be significantly modified by the inserted carbon chain. The orbital hybridization between the host-guest molecules plays a key role in stabilizing the encapsulated double-helix carbon chain. Finally, X-ray powder diffraction (XRD) patterns of stable helical structures inside armchair tubes are presented for guidance of future experimental analyses.     

Electrochemical functionalization of multi-walled carbon nanotubes for solvation and purification

The chemical modification of multi-walled carbon nanotubes using electrolysis is described. It is found that the evolution of the halogens chlorine or bromine on an anode made from a foil of carbon nanotubes couples halogen atoms to the nanotube lattice. Furthermore, oxygen bearing functional groups, such as hydroxyl and carboxyl groups, are formed at the same time aiding solvation of the nanotubes in water or alcohol without any surfactant. Impurities and low grade modified nanotubes remain insoluble. The halogenated carbon nanotubes can be converted with sodium amide or triphenylmethyllithium to add the corresponding functional groups.     

Adaptive fuzzy tracking control design for permanent magnet synchronous motors with output constraint

Nonlinear Dynamics - In this paper, an adaptive fuzzy output feedback position tracking constraint control method is proposed for permanent magnet synchronous motors (PMSM) system. Fuzzy logic...     

半无爪可迹图的度和条件

可迹图即为一个含有Hamilton路的图.令$N[v]=N(v)\cup\{v\}$, $J(u,v)=\{w\in N(u)\cap N(v):N(w)\subseteq N[u]\cup N[v]\}$.若图中任意距离为2的两点$u,v$满足$J(u,v)\neq \emptyset$,则称该图为半无爪图.令$\sigma_{k}(G)=\min\{\sum_{v\in S}d(v):S$为$G$中含有$k$个点的独立集\},其中$d(v)$表示图$G$中顶点$v$的度.本论文证明了若图$G$为一个阶数为$n$的连通半无爪图,且$\sigma_{3}(G)\geq {n-2}$,则图$G$为可迹图; 文中给出一个图例,说明上述结果中的界是下确界; 此外,我们证明了若图$G$为一个阶数为$n$的连通半无爪图,且$\sigma_{2}(G)\geq \frac{2({n-2})}{3}$,则该图为可迹图.     

基于粗糙模糊集的聚类决策及应用

对基于粗糙模糊集的聚类问题进行了研究.首先,定义了粗糙模糊值与粗糙模糊集的相似度,给出了粗糙模糊集相似度的一般表达式;然后利用该公式构建了模糊相似矩阵,进而给出了粗糙模糊集的一种聚类方法;最后以实际算例说明了这种思想.     

A prediction of the acoustical properties of induction cookers based on an FVM–LES-acoustic analogy method

The FVM–LES-acoustic analogy method (FVM–LES-AAM), which is a hybrid prediction technique for the acoustical property computation, is presented and performed in this paper. The FVM–LES-AAM was developed by combining the finite volume method (FVM), the large eddy simulation (LES), and the Ffowcs Williams-Hawkings analogy algorithm (FWH-AA). To predict the acoustical properties of induction cookers, the FVM is used for discretizing the calculation field and building numerical equations, and the LES and FWH-AA are performed for computing the sound sources and predicting the far-field sound, respectively. Using the FVM with the unstructured grids method to discretize the control equation of Navier–Stokes was introduced for illuminating the above numerical simulation procedure. To prove the FVM–LES-AAM method is feasible for predicting the acoustical property of induction cookers, the simulated results were compared with some measured experimental data. The comparisons suggest that the hybrid method is accurate and reliable for the aeroacoustics analysis of induction cookers. Considering the temperature performance, furthermore, some new configurations for the noise reduction of induction cookers were designed, simulated, and discussed. The FVM–LES-AAM prediction technique shows promise as a feasible and computationally affordable approach for not only noise analysis of induction cookers, but also for other aeroacoustics problems in engineering.     

同心球间流动三模类Lorenz系统的动力学行为及数值仿真

讨论了同心球间旋转流动的类Lorenz型方程组的动力学行为及其数值模拟问题,求出了该方程组平衡点,并对其稳定性进行了分析,证明了该方程组吸引子的存在性,对类Lorenz方程组的动力学行为进行了数值模拟,数值试验表明此类Lorenz型方程组存在极限环和奇怪吸引子.     

Navier-Stokes方程五模类Lorenz方程组的动力学行为及数值仿真

本文对平面正方形区域上不可压缩的Navier-Stokes方程,进行傅立叶展开后,截断得到五模类Lorenz方程组.给出了该方程组定常解及其稳定性的讨论,证明了该方程组吸引子的存在性,并对其全局稳定性进行了分析和讨论,数值模拟了雷诺数在一定范围内变化时,类Lorenz方程组的动力学行为.     

模糊输入时滞系统的输出反馈控制及稳定性分析

针对一类状态不可测的模糊输入时滞系统,应用平行分布补偿算法(PDC),设计了模糊观测器,提出了基于模糊观测器的输出反馈控制方法,给出了保证模糊时滞系统渐近稳定的新的充分条件.应用广义Lyapunov函数和线性矩阵不等式方法,证明了模糊输入时滞系统的渐近稳定性,同时给出了控制和观测增益矩阵的分离设计算法.仿真结果进一步验证了所提出的方法和条件的有效性.     

Vaccination of mice against Leishmania mexicana amazonensis with microsomal fraction associated with BCG

Attempts to develop a satisfactory vaccine against New World cutaneous leishmaniasis have been made with varying success. We found that in mice, pretreated subcutaneously with 2×10⁶ BCG organisms 2 weeks prior to immunization at the same site with as low as 10 μg of a microsomal preparation (Pol-F) of Leishmania mexicana amazonensis, a profound alteration was observed in the course of infection produced by inoculation of virulent amastigotes of the same strain. The BCG-Pol-F vaccine preparation was consistently shown to have a protective capacity associated with larger classical cellular immune response (skin test) and higher specific antibody titres in response to leishmanial challenge dose (1 × 10⁶ amastigotes/mouse).